Maxim MAX2452ISE Datasheet

_______________General Description

The monolithic MAX2452 is a quadrature modulator with supporting oscillator and divide-by-8 prescaler. It operates from a single +3V supply and draws only

4.1mA. The modulator accepts differential I and Q baseband signals with amplitudes up to 1.35Vp-p and bandwidths up to 15MHz. It produces a differential output up to 80MHz.

Pulling the CMOS-compatible ENABLE pin low reduces the supply current to 2µA. To minimize spurious feedback, the MAX2452’s internal oscillator is set at twice the IF via external tuning components. The oscillator and associated phase shifters produce differential signals exhibiting low amplitude and phase imbalance, yielding 42dB sideband rejection. The MAX2452 comes in a 16-pin narrow SO package.

________________________Applications

Digital Cordless Phones GSM and North American Cellular Phones Wireless LANs Digital Communications Two-Way Pagers

____________________________Features

♦ IF Output Frequency up to 80MHz ♦ Input Bandwidth up to 15MHz ♦ On-Chip Oscillator with External Tuning Circuit ♦ On-Chip Divide-by-8 Prescaler ♦ Integrated Quadrature Phase Shifters ♦ Self-Biased Differential Baseband Inputs ♦ CMOS-Compatible Enable ♦ 4.1mA Operating Supply Current

2µA Shutdown Supply Current

MAX2452

3V, Ultra-Low-Power

Quadrature Modulator

________________________________________________________________

Maxim Integrated Products

1

16 15 14 13 12 11 10

9

1 2 3 4 5 6 7 8

IF GND V

CC

 N.C. PRE_OUT LO_V

CC

 LO_GND TANK

IF

GND

I

I Q Q

ENABLE

TANK

TOP VIEW

MAX2452

SO

MAX2452

MODULATOR

LOCAL 

OSCILLATOR

÷2

÷2 ÷4

QUADRATURE

PHASE 

GENERATOR

90°

0°

Σ

LO_V

CC

TANK TANK

LO_GND

I I

Q Q

V

CC

PRE_OUT

IF IF

BANDGAP BIAS

GND ENABLE

PRESCALER

11

8 9

10

3 4

5 6

14

12

16

1

72, 15

MASTER BIAS



__________________Pin Configuration

________________Functional Diagram

Call toll free 1-800-998-8800 for free samples or literature.

PART

MAX2452ISE* -20°C to +85°C

TEMP. RANGE PIN-PACKAGE

16 Narrow SO

EVALUATION KIT

AVAILABLE

______________Ordering Information

19-0425; Rev 1; 9/95

* An alternate marking, MAX2452CSE, has been identically tested.

MAX2452

3V, Ultra-Low-Power Quadrature Modulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= LO_VCC= 2.7V to 3.3V, TA= -20°C to +85°C, unless otherwise noted.)

AC ELECTRICAL CHARACTERISTICS

(VCC= LO_VCC= 3.0V, f

OSC

= 140MHz, ENABLE = 2.6V, fII= fQQ= 600kHz, TA= -20°C to +85°C, unless otherwise noted.)

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.

Note 1: Guaranteed by design, not tested. Note 2: The frequency range can be extended in either direction, but has not been characterized. At higher frequencies, the IF

output level may decrease and distortions may increase.

V

CC

, LO_VCCto GND............................................-0.3V to +4.5V

ENABLE, TANK, TANK

, I, I, Q, Q to GND..................VCC+ 0.3V

Continuous Power Dissipation (T

A

= +70°C)

SO (derate 8.33mW/°C above +70°C)..........................667mW

Operating Temperature Range ...........................-20°C to +85°C

Storage Temperature Range ............................–65°C to +165°C

Lead Temperature (soldering, 10sec).............................+300°C

Enable = 0.4V

Enable = VCC- 0.4V

CONDITIONS

kΩ35 44ZII, Z

QQ

Differential Input Impedance

V1.25 1.5 1.75VI, VI, VQ, V

Q

I, I, Q, Q Voltage Level

µA220I

CC OFF

Shutdown Supply Current

mA4.1 7I

CC ON

V2.7 3.3VCC, LO_V

CC

Supply Voltage Range Supply Current

VLO_VCC- 1.1 LO_VCC- 0.8V

TANK

TANK Voltage Level

VLO_VCC- 1.1 LO_VCC- 0.8V

TANK

TANK Voltage Level

VVCC- 1.7 VCC- 1.35V

IF

IF Voltage Level

VVCC- 1.7 VCC- 1.35V

IF

IF Voltage Level

µs10t

ON/OFF

Enable/Disable Time

µA110I

EN

ENABLE Bias Current

V0.4V

ENL

ENABLE Low Voltage

VVCC- 0.4V

ENH

ENABLE High Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

RL= 10kΩ, CL< 6pF, rising edge, TA= +25°C

RL= 10kΩ, CL< 6pF

(Notes 1, 2)

VII= VQQ= 1.2Vp-p

VII= VQQ= 1.2Vp-p, RL= 200kΩ differential, CL< 5pF differential

(Note 1)

CONDITIONS

V/µs60SR

PRE_OUT

PRE_OUT Slew Rate

Vp-p0.35V

PRE_OUT

PRE_OUT Output Voltage

MHz70 140 160f

OSC

Oscillator Frequency Range

dBc-36LO Leakage at Output

dB42Sideband Rejection

degrees<±3I/Q Phase Match

dB<±0.3I/Q Amplitude Match

mVp-p65V

IFIFp-p

IF Differential Output Voltage

MHz15BW

IQ

I and Q Signal Bandwidth

Vp-p1.2 1.35V

IIp-p

, V

QQp-p

Differential Input Voltage

UNITSMIN TYP MAXSYMBOLPARAMETER

MAX2452

3V, Ultra-Low-Power

Quadrature Modulator

_______________________________________________________________________________________

3

4.8

4.7

4.6

4.5

4.4

4.3

4.2

4.1

4.0

3.9

3.8

3.7

3.6

3.5

-30 -10 10 30 50 70 90

MAX2452-01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

SUPPLY CURRENT

vs. TEMPERATURE

V

CC

= 2.7V

V

CC

= 3.3V

V

CC

= 3V

0

2

4

6

8

10

12

14

16

-30 -10 10 30 50 70 90

MAX2452-02

TEMPERATURE (°C)

V

CC

= 2.7V

V

CC

= 3.3V

V

CC

= 3V

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

SUPPLY CURRENT (µA)

-30

-34

-38

-42

-46

-50

-54

-26 -22 -18 -14 -10 -6

MAX2452-03

BASEBAND INPUT (dBV

RMS

)

OUTPUT (dBV

RMS

)

IF OUTPUT

vs. BASEBAND INPUT

Vp-p = 2 2 x 10 (V)

dBV

RMS

20



54

56

58

60

62

64

66

68

70

72

74

2.7

MAX2452-04

VCC (V)

IF OUTPUT (mVp-p)

2.8 2.9 3.0 3.1 3.2 3.3

TA = +85°C

TA = +70°C

TA = +25°C

TA = 0°C

TA = -25°C

IF OUTPUT

vs. SUPPLY VOLTAGE

-50

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

-30 -10 10 30 50 70 90

MAX2452-07

TEMPERATURE (°C)

SIDEBAND REJECTION (dBc)

V

II

= 1.2Vp-p

V

QQ

= 1.2Vp-p

SIDEBAND REJECTION

vs. TEMPERATURE

70

68

66

64

62

60

-30 -10 10 30 50 70 90

MAX2452-05

TEMPERATURE (°C)

IF OUTPUT (mVp-p)

V

CC

= 3V

IF OUTPUT

vs. TEMPERATURE

-50

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

35 40 45 50 55 60 65 70 75 80

MAX2452-06

IF FREQUENCY (MHz)

SIDEBAND REJECTION (dBc)

V

II

= 1.2Vp-p

V

QQ

= 1.2Vp-p

SIDEBAND REJECTION

vs. IF FREQUENCY

-30

-32

-34

-36

-38

-40

-42

-44 8035 40 45 50 55 60 65 70 75

MAX2452-08

IF FREQUENCY (MHz)

LO LEAKAGE (dBc)

LO LEAKAGE

vs. IF FREQUENCY

__________________________________________Typical Operating Characteristics

(VCC= LO_VCC= 3.0V, f

OSC

= 140MHz, ENABLE = 2.6V, fII= fQQ= 600kHz, RL(IF, IF) = 200kΩ differential, CL(IF, IF) < 5pF

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

100mV/

div

PRE_OUT WAVEFORM

MAX2452-09

20ns/div

RL = 10kΩ C

L

< 6pF

MAX2452

3V, Ultra-Low-Power Quadrature Modulator

4 _______________________________________________________________________________________

-60

69.0 70.6

71.0

MODULATOR OUTPUT SPECTRUM

-50

0

MAX2453-10

(MHz)

(dBc)

69.4 70.0

-20

-10

-30

-40

VII = 1.2Vp-p V

QQ

= 1.2Vp-p

____________________________Typical Operating Characteristics (continued)

(VCC= LO_VCC= 3.0V, f

OSC

= 140MHz, ENABLE = 2.6V, fII= fQQ= 600kHz, RL(IF, IF) = 200kΩ differential, CL(IF, IF) < 5pF

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

NAME FUNCTION

1 IF IF Inverting Output

2, 15 GND Ground

3 I Inphase Input 4 I Inphase Inverting Input

8 TANK

Local-Oscillator Resonant Tank Input

7 ENABLE Enable Control, active high

6 Q Quadrature Inverting Input

5 Q Quadrature Input

13 N.C.

No Connect, no internal connection to this pin

12 PRE_OUT

Local-Oscillator Divide-by-8 Prescaled Output

11 LO_V

CC

Local-Oscillator Supply

10 LO_GND Local-Oscillator Ground

9 TANK

Local-Oscillator Resonant Tank Inverting Input

_____________________Pin Description

16 IF IF Output

14 V

CC

Modulator Supply

MAX2452

3V, Ultra-Low-Power

Quadrature Modulator

_______________________________________________________________________________________ 5

_______________Detailed Description

The MAX2452 quadrature modulator integrates several important RF functions on a single chip. It includes differential buffers for the baseband inputs, two doublebalanced mixers, a local oscillator, a quadrature phase generator, and a divide-by-8 prescaler. The prescaler simplifies the implementation of a phase-locked loop. Each of the functional blocks (shown in the

Functional

Diagram

) is described in detail in the following sec-

tions.

Local Oscillator

The local-oscillator section is formed by an emitter-coupled differential pair. Figure 1 shows the equivalent local-oscillator circuit schematic. An external LC resonant tank determines the oscillation frequency, and the Q of this resonant tank determines the phase noise of the oscillator. The oscillation frequency is twice the IF frequency, so that the quadrature phase generator can use two latches to generate precise quadrature signals.

Quadrature Phase Generator

The quadrature phase generator uses two latches to divide the local-oscillator frequency by two, and generates two precise quadrature signals. Internal limiting amplifiers shape the signals to approximate square waves to drive the Gilbert-cell mixers in the modulator. The inphase signal (at half the local-oscillator frequency) is further divided by four for an external phaselocked loop.

Modulator

The modulator accepts up to 1.35Vp-p I and Q differential baseband signals up to 15MHz, and upconverts them to higher-frequency IF signals. Since these inputs are biased internally at around 1.5V, you can improve carrier suppression by externally capacitively coupling the signals into these high-impedance ports (the differential input impedance is approximately 44kΩ). The self-bias design is for very low on-chip offset, resulting in excellent carrier suppression. The IF output is designed to drive a high impedance (>20kΩ), such as an IF buffer or an upconverter mixer.

Prescaler

The prescaler output, PRE_OUT, is buffered and swings typically 0.35Vp-p with a 10kΩ and 6pF load. It can be AC-coupled to the input of a frequency synthesizer.

Master Bias

During normal operation, ENABLE should remain above VCC- 0.4V. Pulling the ENABLE input low shuts off the master bias and reduces the circuit current to 2µA. The master bias section includes a bandgap reference generator and a PTAT (Proportional To Absolute Temperature) current generator.

TANK TANK

Q1 Q2

Q3 Q4

R

L

5k

R

L

5k

L0_V

CC

TO

DIVIDE-BY-2

Figure 1. Local-Oscillator Equivalent Circuit

MAX2452

3V, Ultra-Low-Power Quadrature Modulator

6 _______________________________________________________________________________________

Applications Information

The MAX2452 quadrature modulator is designed to upconvert I and Q baseband signals to IF frequencies up to 80MHz. Figure 2 shows a typical application block diagram, in which the MAX2452 is used for the first upconversion in a dual-conversion transmitter.

Figure 3 shows an implementation of a resonant tank circuit. The inductor, two capacitors, and a dual varactor form the resonant circuit of the oscillator. The frequency range of the oscillator shown in Figure 3 is 130MHz to 160MHz. The inductor is directly connected across the local oscillator’s tank ports so that it will not lock up the oscillator in a stable state during start-up. The two 33pF capacitors increase the Q of the resonant circuit and reduce the VCO gain. They can be changed to meet individual applications requirements. The oscillation frequency can be determined using the following formula:

C

STRAY

, L

STRAY

: parasitic capacitance and induc-

tance.

To alter the oscillation frequency range, change the inductance, the capacitance, or both. Make sure the Q of the resonant tank does not drop below 35.

where REQ= 10kΩ (see Figure 1). The oscillation frequency can be changed by altering

the control voltage, V

CTRL

.

MAX2452

DSP

PROCESSING

0°

I

Q

÷8

90°

UP CONVERTER

Σ

Figure 2. Typical Application Block Diagram

C1 = 33pF

10k

0.1µF

1/2KV1410

L = 100nH

47k

47kC2 = 33pF

TANK

V

CTRL

Figure 3. Typical Resonant Tank Circuit

f

LC

where

C

CC C

C

and

LLL

o

EQ EQ

EQ

VAR

STRAY

EQ STRAY

=

++

+

=+

1

2

1

11122

π

QR

C

L

EQ

=

MAX2452

3V, Ultra-Low-Power

Quadrature Modulator

_______________________________________________________________________________________ 7

________________________________________________________Package Information

DIM



A

A1

B C E e H L

MIN

0.053

0.004

0.014

0.007

0.150 

0.228

0.016

MAX

0.069

0.010

0.019

0.010

0.157 

0.244

0.050

MIN

1.35

0.10

0.35

0.19

3.80 

5.80

0.40

MAX

1.75

0.25

0.49

0.25

4.00 

6.20

1.27

INCHES MILLIMETERS

21-0041A

Narrow SO

SMALL-OUTLINE

PACKAGE

(0.150 in.)

DIM



D D D

MIN

0.189

0.337

0.386

MAX

0.197

0.344

0.394

MIN

4.80

8.55

9.80

MAX

5.00

8.75

10.00

INCHES MILLIMETERS

PINS

8 14 16

1.270.050

L

0°-8°

HE

D

e

A

A1

C

0.101mm

0.004in.

B

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.

8

___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600

MAX2452

3V, Ultra-Low-Power Quadrature Modulator

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.

8

___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600

Maxim MAX2452ISE Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual