Datasheet MAX2721EUP, MAX2720EUP Datasheet (Maxim)

General Description

The MAX2720/MAX2721 are low-cost, high-performance,
direct I/Q modulators designed for use in wideband­CDMA and wireless local-loop (WLL) systems. Their
direct-upconversion architecture reduces system cost,
component count, and board space compared to
devices with dual-conversion architectures.

The MAX2720/MAX2721 include an I/Q modulator, a
variable gain amplifier (VGA), and a power amplifier
(PA) driver. The quadrature modulator accepts differential
baseband I/Q signals and directly modulates an RF
carrier in the 1.7GHz to 2.1GHz range (MAX2720) or
the 2.1GHz to 2.5GHz range (MAX2721). The VGA pro­vides 35dB of output power control. The modulator’s
amplitude and phase balance yield 35dBc of sideband
suppression and 30dBc of carrier suppression. These
devices feature an LO frequency doubler that allows
the external LO source to operate at half-frequency or
full-frequency when disabled.

The MAX2720/MAX2721 operate from a single +2.7V to
+3.3V supply and require only 77mA (MAX2720) or
86mA (MAX2721) of supply current. An additional
20mA of supply current is saved by disabling the
stand-alone PA driver. A low-power shutdown mode
further reduces supply current to less than 0.1µA. The
device is packaged in the small 20-pin TSSOP-EP with
exposed paddle to improve RF performance.

Applications

Wireless Local Loop (WLL)

Wideband CDMA Systems

LMDS/MMDS

2.4GHz Broadband ISM Radios

DCS/PCS Base Stations

Features

♦ RF Frequency Range

1.7GHz to 2.1GHz (MAX2720)

2.1GHz to 2.5GHz (MAX2721)

♦ Integrated I/Q Modulator, LO Doubler, VGA, and

PA Driver

♦ 35dB VGA Gain Control Range

♦ 35dBc Sideband Suppression

♦ 30dBc Carrier Suppression

♦ Low Supply Current

77mA (MAX2720), 86mA (MAX2721)
20mA Reduction with PA Driver Disabled

♦ 0.1µA Supply Current in Shutdown Mode

♦ +2.7V to +3.3V Single-Supply Operation

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

________________________________________________________________ Maxim Integrated Products 1

4

5

20 DRIN

19 GND

18 PC

V

CC

2DROUT

1GND

17

MODOUT

16

15 V

CC

14 Q-

7

I-

6V

CC

GND

13 Q+

12 V

CC

11 LO

9V

CC

8I+

MAX2720/MAX2721

3SHDN

ENX2

0°

90°

PA DRIVER

VGA

LO DOUBLER

LO PHASE SHIFTER

10GND

Σ

x2

BIAS

Functional Diagram

19-1606; Rev 0; 1/00

PART

MAX2720EUP

MAX2721EUP

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

20 TSSOP-EP*

20 TSSOP-EP*

Pin Configuration appears at end of data sheet.

*Exposed paddle.

Ordering Information

For free samples and the latest literature, visit www.maxim-ic.com or phone [phone].
For small orders, phone [phone].

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +3.3V; SHDN = VCC; ENX2 = GND; VPC= 0.5V; no input AC signals applied to I+, I-, Q+, Q-, LO, DRIN. MODOUT

and DROUT = V

CC, TA

= -40°C to +85°C. Typical values are at V

CC.

= +3V, TA= +25°C, unless otherwise noted.)

AC ELECTRICAL CHARACTERISTICS

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, T

A

= +25°C, unless otherwise noted.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VCCto GND..............................................................-0.3V to +6V

ENX2, SHDN, PC, I+, I-, Q+, Q-, LO,

DRIN to GND........................................-0.3V to (V

CC

+ 0.3V)

ENX2, SHDN Continuous Current.....................................±10mA

PC Continuous Current.....................................................±10mA

I+ to I-, Q+ to Q- ....................................................................±2V

MODOUT, DROUT to GND Short-Circuit Duration .................10s

Continuous Power Dissipation (T

A

= +70°C)

20-Pin TSSOP-EP (derate 21.7mW/°C above +70°C) ......1.74W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range ............................ -65°C to +150°C

Lead Temperature (soldering 10s) ................................. +300°C

MAX2721

MAX2720

0.5V < VPC< 2.5V, SHDN = GND

0.5V < VPC< 2.5V

MAX2720, DRIN = GND

MAX2721, DRIN = GND
SHDN = GND

CONDITIONS

86 129

mA

77 119

V

2.7 3.3

Supply Voltage

Supply Current

2.5

µA

-5 5

PC Input Bias Current

µA

-1 1

Logic Input Bias Current

V

0.5

Logic Input Low Voltage

mA

59 86

Supply Current with PA Driver
Disabled

67 96

µA

0.1 10

Shutdown Supply Current

V

2.0

Logic Input High Voltage

UNITSMIN TYP MAXPARAMETER

100kHz < fI= fQ< 2MHz

100kHz < fI+= fQ+< 2MHz

fI= fQ< BW

-1dB

fI= fQ< BW

-1dB

fI= fQ < BW

-3dB

, 0.5V < VPC< 2.5V

fI= fQ< BW

-3dB

, 0.5V < VPC< 2.5V

fI= fQ< BW

-1dB

CONDITIONS

MHz

40

I/Q Input -3dB Bandwidth (Note 2)

MHz

14 20

I/Q BASEBAND INPUTS

I/Q Input -1dB Bandwidth (Note 2)

ns

1

Group Delay Mismatch

ns

1

Group Delay Ripple

pF

5

I/Q Input Capacitance

Ω

18

I/Q Input Resistance Mismatch

mVp-p

200 630

I/Q Differential Input Level

dB

±0.2

I/Q Gain Imbalance

degrees

±1.0

I/Q Phase Imbalance

kΩ

1.6 2.0

I/Q Input Resistance

UNITSMIN TYP MAXPARAMETER

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

_______________________________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, T

A

= +25°C, unless otherwise noted.) (Note 1)

VPC= 2.5V

MAX2721

ENX2 = GND

MAX2721

MAX2720

ENX2 = V

CC

VPC= 2.5V

0.5V < VPC< 2.5V

VPC= 2.5V, I/Q terminated in 50Ω

Slope between VPC= 1V and VPC= 2V

dBm

+8 +14

MAX2721, VPC= 2.5V, ENX2 = VCCor GND,
T

A

= +25°C (Note 3)

Output Third-Order Intercept Point
(Note 4)

MAX2720

CONDITIONS

+3 +6

MAX2721

MAX2721

ENX2 = GND

30 40

ENX2 = V

CC

20 25

ENX2 = GND
ENX2 = V

CC

24 31

ENX2 = GND
ENX2 = V

CC

MAX2720, 0.5V < VPC< 2.5V

+9 +14

2:1

Output VSWR

dBm/Hz

-141 -137

Out-of-Band Noise Density

26 33

MAX2720

MAX2721

VCC= +3.0V + 100mVp-p at 10kHz/300kHz

MAX2720

0.5V < VPC< 2.5V

50 45

MODOUT to LO Input Isolation

1.8:1

1.9:1

LO Input VSWR

2100 2500

MAX2720, VPC= 2.5V, ENX2 = VCCor GND,
T

A

= +25°C (Note 3)

MHz

1700 2100

2100 2500

1050 1250

1.8:1

Frequency Range (Note 3)

dBm

+1 +5

Output 1dB Compression Point

dB/V

19 23

dBc

PC Slope

VPC= 2.5V

41

VPC= 0.5V

Power-Supply Ripple Rejection
(Note 5)

dBm

-12.5 -8.5 -6.0

Output Power, High

MAX2720

-10.5 -5.0 -2.5

MAX2721

MHz

UNITSMIN TYP MAX

850 1050

PARAMETER

LO Frequency Range (Note 3)

1700 2100

28 35

1.6:1

MODULATOR OUTPUT

dBcCarrier Suppression

Sideband Suppression dBc

dB

VPC= 2.5V,
TA= -40°C to +85°C

dB

±1.0 ±1.8

Output Power Variation Over
Temperature

±0.8 ±1.5

MAX2720

MAX2721

MAX2720

MAX2721

dBm

-16 -10

LO Input Power (Note 3)

VPC= 0.5V,
ENX2 = V

CC

or GND

dB

29 35

Power Control Range

28 32

MAX2720

MAX2721

LO BUFFER, LO FREQUENCY DOUBLER, QUADRATURE GENERATOR

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

4 _______________________________________________________________________________________

Note 1: Min/max limits are guaranteed by design and characterization and are not production tested.
Note 2: I/Q input bandwith is determined by the baseband source impedance and the I/Q input capacitance. The bandwith can be

increased by lowering the baseband source impedance.

Note 3: MODOUT output power specifications are met over this frequency range for V

PC

= 2.5V and TA= +25°C.

Note 4 IP3 measured with two tones, f

1

= 500kHz and f2= 600kHz, at 100mVp-p each.

Note 5: Measured relative to desired upconverted signal level.
Note 6 DROUT gain specifications are met over this frequency range at T

A

= +25°C.

Note 7: IP3 measured with two tones, f

1

= 1900MHz and f2= 1901MHz, at -18dBm each.

Note 8: IP3 measured with two tones, f

1

= 2315MHz and f2= 2316MHz, at -18dBm each.

CONDITIONS

MAX2720

MAX2721

MAX2720

MAX2721

UNITSMIN TYP MAXPARAMETER

MAX2720

MAX2720

MAX2721

MAX2720

MAX2721

TA= -40°C to +85°C

MHz

1700 2100

Frequency Range (Note 6)

dBm

+9.5 +12.5

Output 1dB Compression Point

2.6

dB

2.4

Noise Figure

±0.3 ±0.8

2100 2500

dB

11 13.5 15.5

Gain Variation Over Temperature

8.5 11.5 15.5

±0.4 ±0.8

MAX2721 (Note 8)

MAX2720 (Note 7)

MAX2721

dB

19

Reverse Isolation

+20 +24

dB

65

DROUT to LO Input Isolation

1.5:1

Input VSWR

1.5:1

Output VSWR

dBm

+22 +24

Output Third-Order Intercept Point

+8 +11

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, T

A

= +25°C, unless otherwise noted.) (Note 1)

Gain (Note 6) dB

PA DRIVER

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

_______________________________________________________________________________________ 5

0

30

20

10

40

50

60

70

80

90

100

2.7 2.92.8 3.0 3.1 3.2 3.3

SUPPLY CURRENT vs. SUPPLY VOLTAGE

WITH PA DRIVER ENABLED

MAX2720/21toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

TA = +85°C

TA = +25°C

TA = -40°C

ENX2 = GND
ENX2 = V

CC

0

30

20

10

40

50

60

70

80

90

100

2.7 2.92.8 3.0 3.1 3.2 3.3

SUPPLY CURRENT vs. SUPPLY VOLTAGE

WITH PA DRIVER DISABLED

MAX2720/21toc02

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

ENX2 = GND
ENX2 = V

CC

DRIN = GND

TA = +85°C

TA = +25°C

TA = -40°C

-60

-50

-40

-30

-20

-10

0

1700 1800 1900 2000 2100

MODULATOR OUTPUT POWER

vs. RF FREQUENCY

MAX2720/21toc04

RF FREQUENCY (MHz)

OUTPUT POWER (dBm)

TA = +85°C

V

PC

= 2.5V

V

PC

= 1.5V

V

PC

= 0.5V

TA = +25°C

TA = -40°C

-60

-40

-50

-20

-30

-10

0

-19 -13 -11-17 -15 -9 -7 -5

MAX2720/21toc05

LO POWER (dBm)

OUTPUT POWER (dBm) AND CARRIER

AND SIDEBAND SUPPRESSION (dBc)

OUTPUT POWER

CARRIER SUPPRESSION

SIDEBAND SUPPRESSION

MODULATOR PERFORMANCE

vs. LO POWER (ENX2 = GND)

-70

-50

-60

-20

-30

-40

-10

0

-19 -13 -11-17 -15 -9 -7 -5

MAX2720/21toc06

LO POWER (dBm)

OUTPUT POWER (dBm) AND CARRIER

AND SIDEBAND SUPPRESSION (dBc)

OUTPUT POWER

MODULATOR PERFORMANCE

vs. LO POWER (ENX2 = V

CC

)

CARRIER SUPPRESSION

SIDEBAND
SUPPRESSION

Typical Operating Characteristics

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, T

A

= +25°C, unless otherwise noted.) (Note 1)

MAX2720

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

6 _______________________________________________________________________________________

-50

-35

-40

-45

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc10

PC VOLTAGE (V)

OUTPUT POWER (dBm)

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = V

CC

)

2.1GHz

1.9GHz

1.7GHz

-70

-50

-60

-40

-10

-20

-30

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc11

PC VOLTAGE (V)

CARRIER SUPPRESSION (dBc)

MODULATOR CARRIER SUPPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

2.1GHz

1.9GHz

1.7GHz

-50

-35

-40

-45

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc12

PC VOLTAGE (V)

SIDEBAND SUPPRESSION (dBc)

MODULATOR SIDEBAND SUPPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

2.1GHz

1.7GHz

1.9GHz

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

-40

-35

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc08

PC VOLTAGE (V)

CARRIER SUPPRESSION (dBc)

MODULATOR CARRIER SUPPRESSION

vs. PC VOLTAGE (ENX2 = GND)

2.1GHz

1.9GHz

1.7GHz

-60

-40

-50

-20

-30

-10

0

0 1.0 1.50.5 2.0 2.5 3.0

MAX2720/21toc09

PC VOLTAGE (V)

SIDEBAND SUPPRESSION (dBc)

MODULATION SIDEBAND SUPPRESSION

vs. PC VOLTAGE (ENX2 = GND)

2.1GHz

1.9GHz

1.7GHz

MAX2720

-50

-35

-40

-45

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc07

PC VOLTAGE (V)

OUTPUT POWER (dBm)

1.9GHz

1.7GHz

2.1GHz

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = GND)

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

_______________________________________________________________________________________ 7

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

-35

-40

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc14

PC VOLTAGE (V)

CARRIER SUPPRESSION (dBc)

MODULATOR CARRIER SUPPRESSION

vs. PC VOLTAGE (ENX2 = GND)

TA = +85°C

TA = +25°C

TA = -40°C

-55

-60

-20

-30

-40

-10

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc15

PC VOLTAGE (V)

SIDEBAND SUPPRESSION (dBc)

MODULATOR SIDEBAND SUPPRESSION

vs. PC VOLTAGE (ENX2 = GND)

TA = +85°C

TA = +25°C

TA = -40°C

-45

-40

-50

-15

-20

-25

-35

-30

-5

-10

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc16

PC VOLTAGE (V)

OUTPUT POWER (dBm)

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = V

CC

)

TA = +85°C

TA = +25°C

TA = -40°C

-40

-70

-50

-60

-20

-30

-10

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc17

PC VOLTAGE (V)

CARRIER SUPRESSION (dBc)

MODULATOR CARRIER SUPPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

TA = +85°C

TA = +25°C

TA = -40°C

-40

-50

-60

-20

-30

-10

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc18

SIDEBAND SUPRESSION (dBc)

TA = +85°C

TA = -40°C

MODULATOR SIDEBAND SUPPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

TA = +25°C

MAX2720

-50

-35

-40

-45

-15

-10

-20

-30

-25

-5

0

0 1.50.5 1.0 2.0 2.5 3.0

MAX2720/21toc13

PC VOLTAGE (V)

OUTPUT POWER (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

MODULATOR OUTPUT POWER
vs. PC VOLTAGE (ENX2 = GND)

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

8 _______________________________________________________________________________________

-60
10 10,0001000100

MODULATOR OUTPUT POWER
vs. INPUT LEVEL (T

A

= +25°C)

10

-30

-40

-50

0

-10

-20

MAX2720 toc20

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 2.0V

VPC = 1.5V

VPC = 1.0V

VPC = 0.5V

-60
10 10,0001000100

MODULATOR OUTPUT POWER
vs. INPUT LEVEL (T

A

= +85°C)

10

-30

-40

-50

0

-10

-20

MAX2720 toc21

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 2.0V

VPC = 1.5V

VPC = 1.0V

VPC = 0.5V

-20

-15

-30

-25

15

10

0

-5

-10

5

20

25

1.00 0.5 1.5 2.0 2.5 3.0

MODULATOR OUTPUT IP3

vs. PC VOLTAGE

MAX2720/21toc22

PC VOLTAGE (V)

OUTPUT IP3 (dBm)

TA = +25°C

TA = -40°C

TA = +85°C

1.0

1.2

1.6

2.0

2.4

2.8

850 890 930 970 1010 1050

MAX2720-24

FREQUENCY (MHz)

VSWR

LO PORT VSWR

vs. LO FREQUENCY (ENX2 = GND)

1.0

1.4

1.8

2.0

2.4

2.8

1700 1780 1860 1940 2020 2100

MAX2720-25

FREQUENCY (MHz)

VSWR

LO PORT VSWR

vs. LO FREQUENCY (ENX2 = V

CC

)

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

MAX2720

-60
10 10,0001000100

MODULATOR OUTPUT POWER

vs. INPUT LEVEL (T

A

= -40°C)

10

-30

-40

-50

0

-10

-20

MAX2720 toc19

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 2.0V

VPC = 1.5V

VPC = 1.0V

VPC = 0.5V

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

_______________________________________________________________________________________ 9

10

11

12

13

14

15

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER GAIN vs.

SUPPLY VOLTAGE

MAX2720/21toc27

SUPPLY VOLTAGE (V)

GAIN (dB)

TA = +85°C

TA = +25°C

TA = -40°C

20

22

21

23

24

26

25

28

27

29

30

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER OUTPUT IP3

vs. SUPPLY VOLTAGE

MAX2720/21toc28

SUPPLY VOLTAGE (V)

OUTPUT IP3 (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

10

12

11

13

14

16

15

18

17

19

20

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER OUTPUT P1dB

vs. SUPPLY VOLTAGE

MAX2720/21toc29

SUPPLY VOLTAGE (V)

OUTPUT P1dB (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

0

4

2

6

8

12

10

16

14

18

20

1700 1800 1900 2000 2100

PA DRIVER GAIN

vs. RF FREQUENCY

MAX2720/21toc30

RF FREQUENCY (MHz)

GAIN (dB)

TA = +25°C

TA = +85°C

TA = -40°C

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

20

22

21

23

24

26

25

28

27

29

30

1700 1800 1900 2000 2100

PA DRIVER OUTPUT IP3

vs. FREQUENCY

MAX2720/21toc31

FREQUENCY (MHz)

OUTPUT IP3 (dBm)

TA = +25°C

TA = +85°C

TA = -40°C

10

12

11

13

14

16

15

18

17

19

20

1700 1800 1900 2000 2100

PA DRIVER OUTPUT P1dB COMPRESSION

POINT vs. FREQUENCY

MAX2720/21toc32

FREQUENCY (MHz)

OUTPUT P1dB (dBm)

TA = +25°C

TA = -40°C

TA = +85°C

MAX2720

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

0

1.0

0.5

1.5

2.0

3.0

2.5

4.0

3.5

4.5

5.0

1700 1800 1900 2000 2100

PA DRIVER NOISE FIGURE

vs. FREQUENCY

MAX2720/21toc33

FREQUENCY (MHz)

NOISE FIGURE (dB)

TA = +25°C

TA = +85°C

TA = -40°C

-15

-10

-5

10

5

0

15

20

-25 -15 -10-20 -5 50102015

PA DRIVER OUTPUT POWER

vs. INPUT POWER

MAX2720/21toc34

INPUT POWER (dBm)

OUTPUT POWER (dBm)

TA = -40°C

TA = +85°C

TA = +25°C

MAX2720

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 11

-50

-40

-45

-30

-35

-20

-25

-15

-5

-10

0

2100 2200 2300 2400 2500

MODULATOR OUTPUT POWER

vs. RF FREQUENCY

MAX2720 toc38

RF FREQUENCY (MHz)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 1.5V

VPC = 0.5V

TA= +85°C

TA= +25°C

TA= -40°C

-40

-30

-35

-25

-20

-5

-15

-10

0

-19 -17 -15 -13 -11 -9 -7 -5

MODULATOR PERFORMANCE

vs. LO POWER (ENX2 = GND)

MAX2720/21toc39

RF FREQUENCY (MHz)

OUTPUT POWER (dBm) AND CARRIER AND

SIDEBAND SUPPRESSION (dBc)

OUTPUT POWER

CARRIER SUPPRESSION

SIDEBAND SUPPRESSION

-40

-30

-35

-25

-20

-15

-5

-10

0

-19 -17 -15 -13 -9 -7-11 -5

MODULATOR PERFORMANCE

vs. LO POWER (ENX2 = V

CC

)

MAX2720/21toc40

LO POWER (dBm)

OUTPUT POWER (dBm) AND CARRIER AND

SIDEBAND SUPPRESSION (dBc)

OUTPUT POWER

CARRIER SUPPRESSION

SIDEBAND SUPPRESSION

20

30

50

40

70

60

110

100

90

80

120

2.7 2.92.8 3.0 3.1 3.2 3.3

SUPPLY CURRENT vs. SUPPLY VOLTAGE

WITH PA DRIVER ENABLED

MAX2720/21toc35

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

TA = +85°C

TA = +25°C

TA = -40°C

ENX2 = GND
ENX2 = V

CC

20

40

30

60

50

100

90

80

70

120

110

2.7 2.92.8 3.0 3.1 3.2 3.3

SUPPLY CURRENT vs. SUPPLY VOLTAGE

WITH PA DRIVER DISABLED

MAX2720/21toc36

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

TA = +25°C

TA = -40°C

TA = +85°C

DRIN = GND

ENX2 = GND
ENX2 = V

CC

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

MAX2721

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

12 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR SIDEBAND SUPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

MAX2721 TOC46

PC VOLTAGE (V)

SIDEBAND SUPRESSION (dBc)

2.1GHz

2.5GHz

2.3GHz

-45

-35

-40

-20

-25

-30

-5

-10

-15

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = V

CC

)

MAX2721 TOC44

PC VOLTAGE (V)

OUTPUT POWER (dBm)

2.1

GHz

2.3

GHz

2.5

GHz

-45

-35

-40

-20

-25

-30

-5

-10

-15

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR CARRIER SUPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

MAX2721 TOC45

PC VOLTAGE (V)

CARRIER SUPRESSION (dBc)

2.1GHz

2.3GHz

2.5GHz

-40

-30

-35

-25

-20

-15

-5

-10

0

0 0.5 1.0 2.0 2.51.5

3.0

MAX2720/21toc42

PC VOLTAGE (V)

CARRIER SUPPRESSION (dBm)

CARRIER SUPPRESSION vs. PC VOLTAGE

(ENX2 = GND)

2.5GHz

2.1GHz

2.3GHz

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

SIDEBAND SUPRESSION vs. PC VOLTAGE

(ENX2 = GND)

MAX2721 TOC43

PC VOLTAGE (V)

SIDEBAND SUPRESSION (dBc)

2.3GHz

2.1GHz

2.5GHz

MAX2721

-40

-30

-35

-25

-20

-15

-5

-10

0

0 0.5 1.0 1.5 2.0 3.02.5

MAX2720/21toc41

PC VOLTAGE (V)

OUTPUT POWER (dBm)

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = GND)

2.3GHz

2.1GHz

2.5GHz

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 13

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = GND)

MAX2721 TOC47

PC VOLTAGE (V)

OUTPUT POWER (dBm)

TA = +25°C

TA = -40°C

TA = +85°C

-35

-25

-30

-15

-20

-5

-10

0

0 1.0 1.50.5 2.0 2.5 3.0

MODULATOR CARRIER SUPRESSION

vs. PC VOLTAGE (ENX2 = GND)

MAX2721 TOC48

PC VOLTAGE (V)

CARRIER SUPRESSION (dBc)

TA = +85°C

TA = +25°C

TA = -40°C

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR SIDEBAND SUPRESSION

vs. PC VOLTAGE (ENX2 = GND)

MAX2721 TOC49

PC VOLTAGE (V)

SIDEBAND SUPRESSION (dBc)

TA = -40°C

TA = +25°C

TA = +85°C

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR OUTPUT POWER

vs. PC VOLTAGE (ENX2 = V

CC

)

MAX2721 TOC450

PC VOLTAGE (V)

OUTPUT POWER (dBm)

TA = -40°C

TA = +85°C

TA = +25°C

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR CARRIER SUPRESSION

vs. PC VOLTAGE (ENX2) = V

CC

MAX2721 TOC51

PC VOLTAGE (V)

CARRIER SUPPRESSION (dBc)

TA = -40°C

TA = +25°C

TA = +85°C

-40

-35

-30

-25

-20

-15

-10

-5

0

0 1.00.5 1.5 2.0 2.5 3.0

MODULATOR SIDEBAND SUPPRESSION

vs. PC VOLTAGE (ENX2 = V

CC

)

MAX2721 TOC52

PC VOLTAGE (V)

SIDEBAND SUPPRESSION (dBc)

TA = -40°C

TA = +85°C

TA = +25°C

MAX2721

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

14 ______________________________________________________________________________________

-60

-50

-40

-30

-20

-10

0

10

20

10 1000100 10,000

MODULATOR OUTPUT POWER
vs. INPUT LEVEL (T

A

= +85°C)

MAX2721 TOC55

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 1.5V

VPC = 2.0V

VPC = 1.0V

VPC = 0.5V

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 0.5 1.0 1.5 2.0 2.5 3.0

MODULATOR OUTPUT IP3

vs. PC VOLTAGE

MAX2721 TOC56

INPUT LEVEL (mVp-p)

OUTPUT IP3 (dBm)

TA = -40°C

TA = +85°C

TA = +25°C

-20

-15

-10

-25

15

10

-5

0

5

20

25

1.50.5 1.0 2.0 2.5

MODULATOR OUTPUT P1dB

COMPRESSION POINT vs. PC VOLTAGE

MAX2720/21toc57

PC VOLTAGE (V)

OUTPUT P1dB (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

1.0

1.4

1.8

2.0

2.4

2.6

MAX2721toc58

2100 2180 2260 2340 2420 2500

LO PORT VSWR vs. LO FREQUENCY

(ENX2 = V

CC

)

FREQUENCY (MHz)

VSWR

-60

-50

-40

-30

-20

-10

0

10

20

10 1000100 10,000

MODULATOR OUTPUT POWER

vs. INPUT LEVEL (T

A

= +25°C)

MAX2721 TOC54

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 1.5V

VPC = 2.0V

VPC = 1.0V

VPC = 0.5V

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

MAX2721

-60

-50

-40

-30

-20

-10

0

10

20

10 1000100 10,000

MODULATOR OUTPUT POWER
vs. INPUT LEVEL (T

A

= -40°C)

MAX2721 TOC53

INPUT LEVEL (mVp-p)

OUTPUT POWER (dBm)

VPC = 2.5V

VPC = 1.5V

VPC = 2.0V

VPC = 1.0V

VPC = 0.5V

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 15

8

10

9

11

12

14

13

16

15

17

18

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER OUTPUT P1dB

vs. SUPPLY VOLTAGE

MAX2720/21toc63

SUPPLY VOLTAGE (V)

OUTPUT P1dB (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

1.0

1.4

1.6

1.8

2.0

MAX2721toc59

LO PORT VSWR vs. FREQUENCY

(ENX2 = GND)

1050 1090 1130 1170

FREQUENCY (MHz)

1210 1250

VSWR

10

11

13

12

14

15

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER GAIN vs. SUPPLY VOLTAGE

MAX2721 TOC61

SUPPLY VOLTAGE (V)

GAIN (dB)

TA = +25°C

TA = -40°C

TA = +85°C

-2

2

0

4

6

10

8

14

12

16

18

2100 2200 2300 2400 2500

PA DRIVER GAIN

vs. RF FREQUENCY

MAX2720/21toc64

RF FREQUENCY (MHz)

GAIN (dB)

TA = +25°C

TA = +85°C

TA = -40°C

20

22

21

23

24

26

25

28

27

29

30

2.7 2.92.8 3.0 3.1 3.2 3.3

PA DRIVER OUTPUT IP3

vs. SUPPLY VOLTAGE

MAX2720/21toc62

SUPPLY VOLTAGE (V)

OUTPUT IP3 (dBm)

TA = +85°C

TA = -40°C

TA = +25°C

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

20

22

21

23

24

26

25

28

27

29

2100 2200 2300 2400 2500

PA DRIVER OUTPUT IP3

vs. FREQUENCY

MAX2720/21toc65

FREQUENCY (MHz)

OUTPUT IP3 (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

MAX2721

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

16 ______________________________________________________________________________________

0

2

1

3

4

6

5

8

7

9

10

2100 2200 2300 2400 2500

PA DRIVER NOISE FIGURE

vs. FREQUENCY

MAX2720/21toc67

FREQUENCY (MHz)

NOISE FIGURE (dB)

TA = +25°C

TA = -40°C

TA = +85°C

-15

-10

5

10

15

2.0

-25 -15 -10-20 -5 -50102015

PA DRIVER OUTPUT POWER

vs. INPUT POWER

MAX2720/21toc68

INPUT POWER (dBm)

OUTPUT POWER (dBm)

TA = -40°C

TA = +85°C

TA = +25°C

Typical Operating Characteristics (continued)

(MAX2720/MAX2721 EV Kit, VCC= +3.0V, SHDN = VCC, ENX2 = GND, VPC= 2.5V, input I/Q signals driven in quadrature, from a
1kΩ source impedance, single-ended, f

I+

= fQ+= 500kHz, VI+= VQ+= 200mVp-p, PLO= -13dBm, fLO= 950MHz (MAX2720), fLO=

1157.5MHz (MAX2721), P

DRIN

= -12dBm, f

DRIN

= 1900MHz (MAX2720), f

DRIN

= 2315MHz (MAX2721), MODOUT and DROUT ports

are matched to a 50Ω load, TA= +25°C, unless otherwise noted.) (Note 1)

MAX2721

0

4

2

6

8

12

10

16

14

18

20

2100 2200 2300 2400 2500

PA DRIVER OUTPUT P1dB

vs. FREQUENCY

MAX2720/21toc66

FREQUENCY (MHz)

OUTPUT P1dB (dBm)

TA = +25°C

TA = +85°C

TA = -40°C

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 17

Detailed Description

The MAX2720/MAX2721 upconvert in-phase (I) and
quadrature (Q) baseband signals directly to RF
frequencies of 1700MHz to 2100MHz (MAX2720) or
2100MHz to 2500MHz (MAX2721). They are designed
for wideband-CDMA and WLL systems where direct I/Q
modulation of the RF carrier reduces system cost, com­ponent count, and board space compared to
dual-conversion architectures.

Internally, the MAX2720/MAX2721 include an I/Q mod­ulator, a variable gain amplifier (VGA), and a PA driver.
Separate modulator output and PA driver input ports
allow insertion of a bandpass filter between the modulator
and PA driver for increased noise rejection. Disable the
stand-alone PA driver to reduce current consumption.
A low-power shutdown mode further reduces current
consumption to less than 0.1µA. Additionally, a logic­level control disables or enables an internal frequency
doubler that allows the external LO to run at full or half
frequency.

NAME FUNCTION

1, 5, 10, 19, EP GND

Ground. Connect to ground plane with lowest inductance path. Solder exposed paddle
evenly to the board ground plane.

2 DROUT

PA Driver Open-Collector Output Port. Requires an external matching network and a pull­up inductor to VCCfor proper biasing. See Typical Application Circuit for recommended
component values.

PIN

3

SHDN

Shutdown Control Input. Drive with a logic-level high to enable the device. Drive with a logic­level low to disable the device. Bypass with a 1000pF capacitor to ground, as close to the
pin as possible to minimize the amount of external noise coupled onto the control line.

4, 6, 9, 12, 15 V

CC

Supply Voltage Input. Bypass to ground with the specified capacitor as close to the pin as
possible. (See Typical Application Circuit.)

16

ENX2

Logic-Level Enable Input for LO Doubler. Drive with a logic-level low to enable the doubler,
allowing the external LO to run at half-frequency, fLO= f

OUT

/ 2. Drive with a logic-level

high to disable the doubler, and allow the external LO to run at full-frequency, f

LO

= f

OUT

.
Bypass with a 1000pF capacitor to ground as close to the pin as possible to minimize
noise coupled into the control line.

13, 14 Q+, Q-

Quadrature Differential Input Ports. Requires DC-blocking capacitors. See Typical Application
Circuit for recommended component values.

11 LO

Local Oscillator input. Internally matched to 50Ω over the operating frequency band.
Requires a DC-blocking capacitor. See Typical Application Circuit for recommended com­ponent values.

7, 8 I-, I+

In-Phase Differential Input Ports. Requires DC-blocking capacitors. See Typical Application
Circuit for recommended component values.

20 DRIN

PA Driver Amplifier Input Port. Requires an external matching network and a DC-blocking
capacitor that can be part of the matching network. See Typical Application Circuit for rec­ommended component values. Connect to ground to disable the PA Driver and reduce
supply current.

18 PC

Modulator Power Control Input. Apply a voltage between 0.5V to 2.5V to vary the output
power of the I/Q modulator over a 30dB range. Bypass with a 1000pF capacitor to ground
as close to the pin as possible to minimize noise on the control line.

17 MODOUT

Modulator Open-Collector Output Port. Requires an external matching network and a pull­up inductor to VCCfor proper biasing. See Typical Application Circuit for recommended
component values.

Pin Description

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

18 ______________________________________________________________________________________

I/Q Modulator

The MAX2720/MAX2721 modulator is composed of a pair
of matched double-balanced mixers, an active LO quad­rature generator, and a summing amplifier. The pair of
mixers accept differential I/Q baseband signals that
directly modulate the internal 0° and 90° LO signals
applied to the I/Q mixers. An external LO source drives
an internal LO quadrature generator that shifts the phase
of the LO signal applied to the Q mixer by 90° relative to
the LO signal applied to the I channel mixer. The modu­lated output of the I/Q mixers is summed together, and
the undesired sideband is suppressed.

The I+, I-, Q+, and Q- input ports feature high-linearity
buffer amplifiers with a -1dB bandwidth of 20MHz and
a -3dB bandwidth of 38MHz (1kΩ I/Q source imped­ance), and accept differential input voltages up to
630mVp-p. Input bandwith can be extended to beyond
100MHz by lowering the I/Q source impedance. The
ports are internally biased and therefore require DC­blocking capacitors. For single-ended operation,
bypass the I- and Q- ports with a capacitor to ground
equal in value to the DC-blocking capacitors used on
the I+ and Q+ ports. See the Typical Application Circuit
for recommended component values.

Variable Gain Amplifier (VGA)

A VGA follows the summing amplifier of the I/Q modulator.
Apply a voltage between 0.5V and 2.5V to PC to vary
the output power of the modulator over a 32dB span.

The open-collector MODOUT output requires a pull-up
inductor to VCCfor proper biasing, an external matching
network for optimum power transfer, and a DC-blocking
capacitor. Since the MAX2720/MAX2721 are optimized
for different frequency ranges, they require different
output matching networks. See the MAX2720 and

MAX2721 Typical Application Circuit for recommended
component values. See Table 1 for matching to other
frequencies.

LO Buffer and LO Frequency Doubler

The MAX2720/MAX2721 feature an internal LO frequency
doubler that allows the external LO source to run at full or
half frequency (Table 2). Operating the LO at half fre­quency reduces injection-pulling of the voltage-con­trolled oscillator (VCO) from the PA, and reduces the
complexity of designing a high-frequency VCO. An
internal two-pole bandpass filter is integrated before
the LO phase-shift network to help reduce LO harmonic
content and spurious mixing.

To enable the LO frequency doubler, drive ENX2 to a
logic-level low and operate the external LO source at
half the RF carrier frequency. To disable the LO
frequency doubler, drive ENX2 to a logic-level high and
run the external LO source at the RF carrier frequency.
See Table 2 for LO input frequency ranges.

The LO port is a single-ended input that achieves a
VSWR of better than 2:1 over the specified LO input
frequency range. Since the port is internally terminated
with 50Ω, it requires a DC-blocking capacitor. See the
Typical Applications Circuits for recommended compo­nent values. For optimum performance, drive the LO
port with an input power of -16dBm to -10dBm. Driving
the LO port with lower input power levels may affect
quadrature performance, while higher input powers
may increase LO leakage.

PA Driver Amplifier

The PA driver provides a gain of 13.5dB for the
MAX2720 and 11.5dB for the MAX2721. The DRIN
input port requires an external matching network and a

-71.0

-68.9

-93.80.8320.896

-91.3

-66.6

0.861

S22 PHASE

(degrees)

0.9091750

1800

-77.1

75.4

-97.10.8660.878

-94.8

-74.6

0.834

-73.0

0.8681950

2000

-94.70.8070.871

-94.40.8110.8841850

1900

-86.50.8610.914

S22 PHASE

(degrees)

S22 MAGS22 MAG

FREQUENCY

(MHz)

1700

2200

2150

2100

FREQUENCY

(MHz)

2400

2350

2300

2250

Table 1. VGA MODOUT S22 Parameters (VCC= 3.0V, VPC= 2.5V, TA= +25°C)

82.5

-79.6

-104.50.9050.897

-100.50.8910.8922050

2100 2500

2450

MAX2720 MAX2721

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 19

DC-blocking capacitor that can be part of the matching
network. The DROUT open-collector output port
requires an external matching network and a pull-up
inductor to VCCfor proper biasing. The pull-up inductor
is incorporated as part of the matching network. See
the MAX2720 and MAX2721 Typical Application Circuit
for recommended component values. Refer to Table 3
for matching to other frequencies.

If the additional gain of the PA driver is not required,
disable the PA driver to reduce current consumption.
To disable the PA driver, short pin 20 (DRIN) to ground
and leave pin 2 unconnected.

Shutdown

Apply a logic-level high to the SHDN pin to enable the
MAX2720/MAX2721. Apply a logic-level low voltage to
disable the device and reduce supply current to less
than 0.1µA.

Applications Information

Layout Considerations

A properly designed PC board is an essential part of
any RF circuit. A ground plane is essential. Keep RF
signal lines as short as possible to reduce losses, radi­ation, and inductance. Use separate, low-inductance
vias to the ground plane for each pin. For best perfor­mance, solder the exposed pad on the bottom of the
device package evenly to the board ground plane.
Remove the ground plane under the external VCO and
lowpass filters to reduce the effects of parasitic capaci-

tance. In direct I/Q modulator applications, radiated
power from the PA can couple into the VCO tank. To
reduce PA injection-pulling, the external VCO should be
housed in a separate shielded compartment if possible.

Power-Supply, Logic, and PC

Input Bypassing

Proper voltage supply bypassing is essential for high-fre­quency circuit stability. With the exception of pin 6,
bypass all VCCpins with a 470pF capacitor as close to
the VCCpins as possible. The decoupling capacitor for
pin 6 also serves as part of an on-chip matching network,
so it should be chosen to resonate out series inductance
on the board. Some empirical adjustment may yield
increased output power. See the MAX2720/MAX2721
Typical Application Circuit for suggested values.

Bypass the ENX2, SHDN, and PC inputs with a 1000pF
capacitor to ground to minimize noise injected into the
device. Use a series resistor (10kΩ typ) to further
reduce coupling of high-frequency signals into the
device.

Voltage supply layout is also critical to achieve optimum
performance. The IC has several RF processing stages
that use the various VCCpins, and while they have
on-chip decoupling, off-chip interaction between them
may degrade gain, linearity, carrier suppression, and
output power control range. The supplies associated
with pins 2, 6, 15 (MAX2721 only), and 17 lie directly in
the RF signal path. Pins 4, 12, and 15 carry LO signal
currents, so it is important to keep them from interacting
with the RF signal path to prevent poor carrier suppres­sion. The VGA generates discarded signal currents on
pin 4, which also need to be kept away from the signal
path supplies. Because there is a great deal of gain
following from the first RF stage, it is also important to
prevent coupling from pins 2, 4, 15, and 17 to pin 6;
excessive coupling may degrade stability.

2100 to 2500

1050 to 1250

1700 to 2100

MAX2721

850 to 1050Low

High

MAX2720

LO INPUT FREQUENCY RANGE (MHz)

ENX2

LOGIC LEVEL

Table 2. LO Input Frequency Range

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

20 ______________________________________________________________________________________

Table 3. PA Driver S-Parameters (VCC= 3.0V, TA= +25°C)

0.125

0.110

0.117

0.118

0.123

0.106

0.106

2.848

3.176

3.087

3.013

2.929

3.360

3.268

-97.8

-133.9

-153.1

-141.0

-144.9

-142.7

47.02500 0.425 40.9 0.015130.3

-138.9

80.4

71.7

63.5

55.4

96.2

2350

2300 0.456 75.9 0.051

0.462 67.9 0.042

87.4

2450

2400 0.447

135.8

59.7

135.3

0.031

0.437 51.6 0.026

132.9

132.2

2250

2200 0.475 88.0 0.055

0.473 84.2 0.046

139.0

136.9

0.1023.492 -138.0104.22150 0.470 97.2 0.066141.3

0.100

FREQUENCY

(MHz)

S11 MAG S21 PHASE S22 MAG

0.105

0.093

0.093

0.091

0.096

S12 MAG

0.092

0.097

3.690

3.567

4.370

4.160

3.946

3.801

S21 MAG

4.708

4.389

S22 PHASE

-120.3

-128.8

-109.2

-118.4

-100.8

-111.0

-82.4

120.4

112.32100

2050 0.440 112.8 0.083

0.452 104.9 0.082

142.8

-99.5

153.5

144.3

135.2

128.4

S21 PHASE

178.1

142.9

1900

1850 0.418 138.2 0.123

0.449 129.7 0.095

161.7

2000

1950 0.421

149.4

128.7

145.3

0.082

0.425 121.2 0.091

140.1

142.8

1800

1700 0.321

S11 PHASE

164.7 0.162

0.383 147.2 0.142

151.6

152.0

0.0944.588 -90.3171.51750 0.347 154.2 0.158152.7

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 21

Typical Application Circuit

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

12

11

9

10

V

CC

DROUT

GND

I+

I-

V

CC

GND

GND

V

CC

SHDN

DRIN

GND

PC

MODOUT

V

CC

Q-

Q+

V

CC

LO

ENX2

MAX2720
MAX2721

0.1µF

V

CC

470pF

0.1µF

8pF (5pF*)

V

CC

470pF

V

CC

1000pF

100k

2.0pF

470pF

3.9nH

V

CC

PA DRIVER

OUTPUT

PA DRIVER
INPUT

SHUTDOWN

CONTROL

LO DOUBLER
ENABLE

VGA POWER

CONTROL

I MODULATION

Q MODULATION

LO INPUT

47pF

V

CC

470pF

0.1µF

3pF

0.1µF

470pF

V

CC

1.0pF (27pF*)

470pF

1.5nH
(1.2nH*)

0nH

(3.3nH*)

V

CC

MODOUT
OUTPUT

10k

1000pF

100k

1000pF

*COMPONENT VALUE FOR MAX2721 0NLY.

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

22 ______________________________________________________________________________________

Chip Information

TRANSISTOR COUNT: 1041

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

DRIN

GND

PC

MODOUTV

CC

DROUT

GND

TOP VIEW

V

CC

Q-

Q+I+

I-

V

CC

GND

12

11

9

10

V

CC

LOGND

V

CC

MAX2720
MAX2721

TSSOP-EP

SHDN

ENX2

Pin Configuration

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

______________________________________________________________________________________ 23

Package Information

TSSOP.EPS

MAX2720/MAX2721

1.7GHz to 2.5GHz, Direct I/Q Modulator with
VGA and PA Driver

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

NOTES