Datasheet MAX2510EEI Datasheet (Maxim)

Page 1

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________________General Description

The MAX2510 is a highly integrated IF transceiver for digital wireless applications. It operates from a +2.7V to +5.5V supply voltage and features four operating modes for advanced system power management. Supply current is reduced to 0.2µA in shutdown mode.

In a typical application, the receiver downconverts a high IF/RF (up to 600MHz) to a low IF (up to 30MHz) using a double-balanced mixer. Additional functions included in the receiver section are an IF buffer that can drive an off-chip filter, an on-chip limiting amplifier offering 90dB of received-signal-strength indication (RSSI), and a robust differential limiter output driver designed to directly drive a CMOS input. The transmitter section upconverts I and Q baseband signals to an IF in the 100MHz to 600MHz range using a quadrature modulator. The transmit output is easily matched to drive a SAW filter with an adjustable output from 0dBm to -40dBm and excellent linearity.

The MAX2511 has features similar to the MAX2510, but upconverts a low IF with an image-reject mixer. The MAX2511 downconverter also offers image rejection with a limiter/RSSI stage similar to that of the MAX2510.

________________________Applications

PWT1900, Wireless Handsets, and Base Stations PACS, PHS, DECT, and Other PCS Wireless

Handsets and Base Stations 400MHz ISM Transceivers IF Transceivers Wireless Data Links

____________________________Features

♦ +2.7V to +5.5V Single-Supply Operation ♦ Complete Receive Path: 600MHz (max) 1st IF to

30MHz (max) 2nd IF

♦ Unique, Wide-Dynamic-Range Downconverter

Mixer Offers -8dBm IIP3, 11dB NF

♦ 90dB Dynamic-Range Limiter with High-Accuracy

RSSI Function

♦ Differential Limiter Output Directly Drives

CMOS Input

♦ 100MHz to 600MHz Transmit Quadrature

Modulator with 41dB Sideband Suppression

♦ 40dB Transmit Gain-Control Range; Up to +1dBm

Output Power

♦ Advanced Power Management (four modes) ♦ 0.2µA Shutdown Supply Current

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

________________________________________________________________

Maxim Integrated Products

28 27 26 25 24 23 22 21 20 19 18 17 16 15

1 2 3 4 5 6 7 8

9 10 11 12 13 14

VREF MIXOUT GND RXIN TXOUT TXOUT

RXIN V

GND V

Q Q

LIMOUT

RXEN

TXEN

GND

RSSI

LIMIN

QSOP

TOP VIEW

MAX2510

___________________Pin Configuration

19-1296; Rev 1; 1/98

PART

MAX2510EEI -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

28 QSOP

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

_______________Ordering Information

Typical Operating Circuit appears on last page.

Page 2

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V; 0.01µF across CZ and CZ; LO, LO open; MIXOUT tied to VREF through a 165Ω resistor; GC = 0.5V; RXIN,

RXIN open; LIMIN tied through 50Ω to VREF; LIMOUT, LIMOUT = open; RXEN, TXEN = high; bias voltage at I, I, Q, Q = 1.4V;

= -40°C to +85°C; unless otherwise noted. Typical values are at TA= +25°C.)

AC ELECTRICAL CHARACTERISTICS

(MAX2510 test fixture; VCC= +3.0V; RXEN = TXEN = low; 0.01µF across CZ and CZ; MIXOUT tied to VREF through 165Ω resistor; TXOUT and TXOUT loaded with 100Ω differential; LO terminated with 50Ω, LO AC grounded; GC open; LIMOUT, LIMOUT are AC coupled to 250Ω load; 330pF at RSSI pin; 0.1µF connected from VREF pin to GND; P

RXIN, RXIN

= -30dBm differentially driven (input

matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I, Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I,Q

= 200kHz; f

LO, LO

= 230MHz; P

= -13dBm;

= +25°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.

VCCto GND .............................................................-0.3V to 8.0V

to Any Other VCC........................................................±0.3V

I, I, Q, Q to GND.........................................-0.3V to (V

+ 0.3V)

I to I, Q to Q Differential Voltage............................................±2V

RXIN to RXIN Differential Voltage..........................................±2V

LOIN to LOIN Differential Voltage..........................................±2V

LIMIN Voltage .............................(VREF - 1.3V) to (VREF + 1.3V)

RXEN, TXEN, GC Voltage...........................-0.3V to (V

+ 0.3V)

RXEN, TXEN, GC Input Current............................................1mA

RSSI Voltage...............................................-0.3V to (V

+ 0.3V)

Continuous Power Dissipation (T

= +70°C)

QSOP (derate 10mW/°C above +70°C)........................650mW

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

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

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

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

CONDITIONS

V2.7 3.0 5.5Operating Voltage Range

UNITSMIN TYP MAXPARAMETER

RXEN, TXEN V2.0Digital Input Voltage High

RXEN, TXEN = 2.0V µA

630

Digital Input Current High

RXEN, TXEN V0.4Digital Input Voltage Low

Receive mode, RXEN = high, TXEN = low

14 20

Standby mode, RXEN = high, TXEN = high

0.5 1

RXEN, TXEN = 0.4V

Transmit mode, RXEN = low, TXEN = high

17 25

µA-5 0.1Digital Input Current Low

Shutdown mode, RXEN = low, TXEN = low µA

0.2 5

Supply Current

VCC/ 2 -

CC / 2

/ 2 +

100mV 100mV

VREF Voltage

(Note 1) kΩ

50 85

GC Input Resistance

(Note 2) MHz100 600Input Frequency Range

Single sideband dB11Noise Figure

TA= +25°C

20.5 22.5 25

Conversion Gain

CONDITIONS

(Note 4) dBm-18.5Input 1dB Compression Point

Two tones at 240MHz and 240.2MHz,

-30dBm per tone

dBm-8Input Third-Order Intercept

UNITSMIN TYP MAXPARAMETER

dBc49LO to RXIN Isolation

Standby to RX or TX (Note 5) µs5Power-Up Time

DOWNCONVERTER (RXEN = high)

19.9 25.5

TA= -40°C to +85°C (Note 3)

Page 3

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

_______________________________________________________________________________________ 3

AC ELECTRICAL CHARACTERISTICS (continued)

RXIN, RXIN

= -30dBm differentially driven (input

matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I, Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I,Q

= 200kHz; f

LO, LO

= 230MHz; P

= -13dBm;

= +25°C; unless otherwise noted.)

Note 1: This pin is internally terminated to approximately 1.35V through the specified resistance. Note 2: Downconverter gain is typically greater than 20dB. Operation outside this frequency range is possible but has not been

characterized.

Note 3: Guaranteed by design and characterization.

LIMOUT, LIMOUT

mV±270 ±300 ±350

-85dBm to 5dBm

Limiter Output Voltage Swing

-75dBm to 5dBm degrees±4.5

Phase Variation

90Minimum Monotonic RSSI Range

-75dBm to 5dBm from 50Ω mV/dB20RSSI Slope

CONDITIONS

-75dBm to 5dBm dB80Minimum Linear RSSI Range

UNITSMIN TYP MAXPARAMETER

(Note 6) dBm-86

At LIMIN input of +5dBm

RSSI Maximum Zero-Scale Intercept

TA= +25°C

±0.5 ±2.0

RSSI Relative Error (Notes 6, 7)

1.8Maximum-Scale RSSI Voltage

At LIMIN input of -75dBm V0.25Minimum-Scale RSSI Voltage

I, I, Q, Q inputs are 250mVp-p centered

around

this voltage, GC = 2.0V (Note 9)

(Note 8) MHz100 600Frequency Range

1.3

1.2

I, I, Q, Q Allowable Common-Mode Voltage Range

GC = 0.5V -41

GC = 2.0V (Note 9)

GC = open -16

-3

90° phase difference between I and Q inputs; GC = 2V

dBc30 40Unwanted Sideband Suppression

dBm

-2.5 1

Output Power

GC = 2V (Note 11) -33

Output IM3 Level

GC = 2V (Note 11) dBc-51Output IM5 Level

GC = 0.5V (Note 11)

dBc

-49

I, Q are 500mVp-p while I, Q are

held

at this DC

voltage (Note 9)

1.4

1.3

90° phase difference between I and Q inputs; measured to fundamental tone; GC = 2V

dBc30 44LO Rejection

TA= -40°C to +85°C (Note 3) ±3.0

TA= +25°C

(Note 3) MHz70 80

I, I, Q, Q 1dB Bandwidth

LIMITING AMPLIFIER AND RSSI (RXEN = high, f

LIMIN

= 10MHz, P

LIMIN

= -30dBm from 50Ω source, unless otherwise noted)

TRANSMITTER (TXEN = high)

TA= -40°C to +85°C

Page 4

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

4 _______________________________________________________________________________________

__________________________________________Typical Operating Characteristics

(MAX2510 EV kit; VCC= +3.0V; 0.01µF across CZ and CZ; MIXOUT tied to VREF through 165Ω resistor; TXOUT and TXOUT loaded with 100Ω differential; LO terminated with 50Ω; LO AC grounded; GC open; LIMOUT, LIMOUT open; 330pF at RSSI pin; 0.1µF connected from VREF pin to GND; P

RXIN, RXIN

= -30dBm differentially driven (input matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I,

Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I, Q

= 200kHz; f

LO, LO

= 230MHz; PLO= -13dBm; TA= +25°C; unless otherwise noted.)

-40 0-20 20 40 60 80 100

SUPPLY CURRENT

vs. TEMPERATURE

MAX2510toc01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

STANDBY

6 4 2

2.5 3.53.0 4.0 4.5 5.0 5.5

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX2510toc02

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

STANDBY

0 0.40.2 0.6 1.21.00.8 1.4 1.6 1.8 2.0

TRANSMITTER SUPPLY CURRENT

vs. GC VOLTAGE

MAX2510toc03

GC VOLTAGE (V)

SUPPLY CURRENT (mA)

Note 4: Driving RXIN or RXIN with a power level greater than the 1dB compression level forces the input stage out of its linear

range, causing harmonic and intermodulation distortion. The RSSI output increases monotonically with increasing input levels beyond the mixer’s 1dB compression level. Input 1dB compression point is limited by MIXOUT voltage swing, which is approximately 2Vp-p into a 165Ω load.

Note 5: Assuming the supply voltage has been applied, this includes limiter offset-correction settling and Rx or Tx bias stabilization

time. Guaranteed by design and characterization.

Note 6: The RSSI maximum zero-scale intercept is the maximum (over a statistical sample of parts) input power at which the RSSI

output would be 0V. This point is extrapolated from the linear portion of the RSSI Output Voltage vs. Limiter Input Power graph in the

Typical Operating Characteristics

. This specification and the RSSI slope define the RSSI function’s ideal behavior (the slope and intercept of a straight line), while the RSSI relative error specification defines the deviations from this line. See the

Typical Operating Characteristics

for the RSSI Output Voltage vs. Limiter Input Power graph.

Note 7: The RSSI relative error is the deviation from the best-fitting straight line of the RSSI output voltage versus the limiter input

power. This number represents the worst-case deviation at any point along this line. A 0dB relative error is exactly on the ideal RSSI transfer function. The limiter input power range for this test is -75dBm to 5dBm from 50Ω. See the

Typical

Operating Characteristics

for the RSSI Relative Error graph.

Note 8: Transmit sideband suppression is typically better than 35dB. Operation outside this frequency range is possible but has

not been characterized.

Note 9: Output IM3 level is typically better than -29dBc. Note 10: The output power can be increased by raising GC above 2V. Refer to the Transmitter Output Power vs. GC Voltage and

Frequency graph in the

Typical Operating Characteristics

Note 11: Using two tones at 400kHz and 500kHz, 250mVp-p differential per tone at I, I, Q, Q.

Page 5

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

_______________________________________________________________________________________

0.4

0.2

0.8

0.6

1.0

1.2

2.5 3.5 4.03.0 4.5 5.0 5.5

SHUTDOWN SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX2510toc04

SUPPLY VOLTAGE (V)

SHUTDOWN SUPPLY CURRENT (µA)

TA = +85°C

TA = -40°C

TA = +25°C

2.5 3.5 4.03.0 4.5 5.0 5.5

DOWNCONVERTER MIXER CONVERSION

GAIN vs. SUPPLY VOLTAGE

AND TEMPERATURE

MAX2510toc05

VOLTAGE (V)

GAIN (dB)

TA = +85°C

= +25°C

TA = -40°C

0 400 500200 300100 600 700 800 900 1000

DOWNCONVERTER MIXER CONVERSION

GAIN vs. RXIN FREQUENCY

MAX2510toc06

RF FREQUENCY (MHz)

GAIN (dB)

MISMATCH LOSS COMPENSATED

-20

-17

-18

-19

-16

-15

-14

-13

-12

-22

-21

2.5 3.53.0 4.0 4.5 5.0 5.5

RECEIVE MIXER INPUT 1dB

COMPRESSION POINT vs. SUPPLY VOLTAGE

MAX2510toc07

SUPPLY VOLTAGE (V)

INPUT 1dB COMPRESSION (dBm)

TA = +85°C

TA = +25°C

TA = -40°C

100

200 150

300 250

350

450 400

500

30 150 21090 270 330 390 450 510

RXIN INPUT IMPEDANCE

vs. FREQUENCY

MAX2510toc08

FREQENCY (MHz)

REAL IMPEDANCE (Ω)

IMAGINARY

SINGLE-ENDED

REAL

____________________________ Typical Operating Characteristics (continued)

RXIN, RXIN

= -30dBm differentially driven (input matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I,

Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I, Q

= 200kHz; f

LO, LO

= 230MHz; PLO= -13dBm; TA= +25°C; unless otherwise noted.)

Page 6

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

6 _______________________________________________________________________________________

-5

-3

-4

-1

-2

1 0

4 3

-95 -75 -55 -35 -15 5

RSSI RELATIVE ERROR vs. LIMIN INPUT

POWER AND TEMPERATURE

MAX2510toc10

LIMITER INPUT POWER (dBm, 50Ω)

RSSI ERROR (dB)

TA = +25°C

TA = -40°C

= +25°C

TA = +85°C

0.4

0.2

0.8

0.6

1.2

1.0

1.4

1.8

1.6

2.0

-120 -100 -80 -60 -40 -20 0 20

RSSI OUTPUT VOLTAGE vs. LIMIN INPUT

POWER AND TEMPERATURE

MAX2510toc10a

LIMITER INPUT POWER (dBm, 50Ω)

RSSI VOLTAGE (V)

OUT

= -40°C

OUT

= +85°C

OUT

= +25°C

0.4

0.2

0.8

0.6

1.2

1.0

1.4

1.8

1.6

2.0

-80 -60 -50 -40-70 -30 -20 -10 0

RSSI OUTPUT VOLTAGE

vs. RXIN INPUT POWER

MAX2510toc11

RXIN INPUT POWER (dBm)

RSSI VOLTAGE (V)

-60

-40

-50

-20

-30

-10

0.5 0.9 1.10.7 1.3 1.5 1.7 1.9

TRANSMITTER OUTPUT POWER

vs. GC VOLTAGE AND FREQUENCY

MAX2510toc12

GC VOLTAGE (V)

OUTPUT POWER (dBm)

230MHz

200MHz

500MHz

-25

-15

-20

-5

-10

0 400200 600 800 1000

TRANSMITTER OUTPUT POWER

vs. FREQUENCY

MAX2510toc12a

FREQUENCY (MHz)

OUTPUT POWER (dBm)

GC = 2.0V

-55

-50

-45

-40

-35

-30

0 0.8 1.00.4 0.60.2 1.2 1.4 1.6 1.8 2.0

TRANSMITTER IM3 LEVELS

vs. GC VOLTAGE

MAX2510toc13

GC VOLTAGE (V)

IM3 LEVELS (dBc)

-60

-50

-40

-20

-10

-30

0 0.40.2 0.6 1.21.00.8 1.4 1.6 1.8 2.0

TRANSMITTER OUTPUT 1dB COMPRESSION

POINT vs. GC VOLTAGE

MAX2510toc15

GC VOLTAGE (V)

OUTPUT 1dB COMPRESSION (dBm)

TA = +85°C

TA = -40°C

TA = +25°C

____________________________ Typical Operating Characteristics (continued)

RXIN, RXIN

= -30dBm differentially driven (input matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I,

Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I, Q

= 200kHz; f

LO, LO

= 230MHz; PLO= -13dBm; TA= +25°C; unless otherwise noted.)

Page 7

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

_______________________________________________________________________________________

0.2

0.4

0.6

0.8

1.0

2.5 3.53.0 4.0 4.5 5.0 5.5

TRANSMITTER OUTPUT POWER

vs. SUPPLY VOLTAGE

MAX2510toc15

SUPPLY VOLTAGE (V)

OUTPUT POWER (dBm)

TA = +25°C

TA = -40°C

TA = +85°C

-30

-24

-26

-28

-20

-22

-12

-14

-16

-18

-10

50 100 150 200 250 300 350 400

OUTPUT POWER

vs. BASEBAND INPUT VOLTAGE

MAX2510toc16

BASEBAND INPUT VOLTAGE (mVp)

OUTPUT POWER (dBm)

GC = OPEN

0 400200 600 800 1000

TRANSMITTER SIDEBAND SUPPRESSION

vs. RF FREQUENCY

MAX2510toc17

RF FREQUENCY (MHz)

SIDEBAND SUPPRESSION (dB)

-1000

-800

Tx MODE REAL

-900

-600

-700

-400

-500

-300

-200

-100

100

200 400300 500

TRANSMITTER DIFFERENTIAL

OUTPUT IMPEDANCE vs. FREQUENCY

MAX2510toc18

FREQUENCY (MHz)

REAL AND IMAGINARY IMPEDANCE (Ω)

Tx OFF IMAGINARY

Tx MODE IMAGINARY

Tx OFF REAL

-154

-150

-152

-146

-148

-142

-144

-140

-136

-138

-134

0 0.4 0.6 0.80.2 1.0 1.2 1.4 1.81.6 2.0

TRANSMIT NOISE POWER

vs. GC VOLTAGE

MAX2510toc19

GC VOLTAGE (V)

OUTPUT NOISE POWER (dBm/Hz)

Af = 200kHz

-18.0

-17.0

-17.5

-16.0

-16.5

-15.0

-15.5

-14.5

-13.5

-14.0

-13.0

-20 -16 -14 -12-18 -10 -8 -6 -2-4 0

TRANSMITTER OUTPUT POWER

vs. LO POWER

MAX2510toc20

LO POWER (dBm)

OUTPUT POWER (dBm)

____________________________ Typical Operating Characteristics (continued)

RXIN, RXIN

= -30dBm differentially driven (input matched); f

RXIN, RXIN

= 240MHz; bias voltage at I, I,

Q, Q = 1.4V; V

I,Q

= 500mVp-p; f

I, Q

= 200kHz; f

LO, LO

= 230MHz; PLO= -13dBm; TA= +25°C; unless otherwise noted.)

Page 8

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

8 _______________________________________________________________________________________

Pin Description

Offset-Correction Capacitor Pins. Connect a 0.01µF capacitor between CZ and CZ.CZ, CZ

2, 3

Limiter Input. Connect a 330Ω (typical) resistor to VREF for DC bias, as shown in the

Typical Operating

Circuit.

LIMIN1

FUNCTIONNAME

Gain-Control Pin. Applying a DC voltage to GC between 0V and 2.0V adjusts the transmitter gain by more than 40dB. GC is internally terminated to 1.35V via an 85kΩ resistor.

GC5

Received Signal-Strength Indicator Output. The voltage on RSSI is proportional to the signal power at LIMIN. The RSSI output sources current pulses into a 330pF (typical) external capacitor. This output is internally terminated with 11kΩ, and this RC time constant sets the decay time.

RSSI4

Local-Oscillator Input Ground. Connect to PC board ground plane with minimal inductance.GND7

Differential LO Inputs. In a typical application, externally terminate LO with 50Ω to ground, then AC couple into LO. AC terminate LO directly to ground for single-ended operation, as shown in the

Typical

Operating Circuit.

LO, LO

6, 9

Baseband In-Phase Inputs. The differential voltage across these inputs forms the quadrature modulator’s I-channel input. The signal input level is typically up to 500mVp-p centered around a 1.4V (typical) DC bias level on I.

I, I

15, 16

Differential Outputs of the Limiting Amplifier. These outputs are complementary emitter followers capable of driving 250Ω single-ended loads to ±300mV.

LIMOUT,

LIMOUT

13, 14

Baseband Quadrature-Phase Inputs. The differential voltage across these inputs forms the quadrature modulator’s Q-channel input. The signal input level is typically up to 500mVp-p, centered around a 1.4V (typical) DC bias level on Q.

Q, Q

17, 18

Receiver Enable Pin. When high, RXEN enables the receiver if TXEN is low. If both RXEN and TXEN are high, the part is in standby mode; if both are low, the part is in shutdown. See the

Power Management

section for details.

RXEN12

Transmitter-Enable Pin. When high, TXEN enables the transmitter if RXEN is low. If both TXEN and RXEN are high, the part is in standby mode; if both are low, the part is in shutdown. See the

Power

Management

section for details.

TXEN11

Differential Outputs of the Upconverter. In a typical application, these open-collector outputs are pulled up to VCCwith two external inductors and AC coupled to the load. See the

Applications Information

sec-

tion for more details, including information on impedance matching these outputs to a load.

TXOUT, TXOUT

23, 24

Differential Inputs of the Downconverter Mixer. An impedance-matching network may be required in some applications. See the

Applications Information

section for details.

RXIN,

RXIN

22, 25

Reference Voltage Pin. VREF provides an external bias voltage for the MIXOUT and LIMIN pins. Bypass this pin with a 0.1µF capacitor to ground. The VREF voltage is equal to VCC/ 2. See the

Typical

Operating Circuit

for more information.

VREF28

Receiver Mixer Ground. Connect to PC board ground plane with minimal inductance.GND26

General-Purpose VCCPins. Bypass with a 0.047µF low-inductance capacitor to GND.V

19, 21

Local-Oscillator Input VCCPin. Bypass directly to local-oscillator input ground (pin 8).V

Limiter Ground. Connect to PC board ground plane with minimal inductance.GND10

Receiver/Transmitter Ground. Connect to PC board ground plane with minimal inductance.GND20

Single-Ended Output of the Downconverter Mixer. This pin is high-impedance and must be biased to the VREF pin through an external terminating resistor whose value depends on the interstage filter characteristics. See the

Applications Information

section for details.

MIXOUT27

Page 9

_______________Detailed Description

The following sections describe each of the blocks shown in Figure 1.

Receiver

The receiver consists of two basic blocks: the downconverter mixer and the limiter/received-signal-strength indicator (RSSI) section.

The receiver inputs are the RXIN and RXIN pins, which should be AC coupled and may require a matching network as shown in the

Typical Operating Circuit

. To design a matching network for a particular application, consult the RXIN Input Impedance plots in the

Typical

Operating Characteristics

, as well as the

Applications

Information

sections.

Downconverter Mixer

The downconverter consists of an a double-balanced mixer and an output buffer. The MIXOUT output, a singleended current source, can drive a shunt-terminated

330Ω filter (165Ω load) to more than 2Vp-p over the entire supply range, providing excellent dynamic range. The local oscillator (LO) input is buffered and drives the mixer.

Limiter

The signal passes through an external IF bandpass filter into the limiter input (LIMIN). LIMIN is a singleended input that is biased at the VREF pin voltage. The open-circuit input impedance is typically greater than 10kΩ to VREF. For proper operation, LIMIN must be tied to VREF through the filter-terminating impedance (which should be less than 1kΩ). The limiter provides a constant output level, which is largely independent of the limiter input signal level over a 90dB input range. The low-impedance limiter outputs provide 600mVp-p single-ended swing (1.2Vp-p differential swing) and can drive CMOS inputs directly.

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

_______________________________________________________________________________________ 9

RXIN

VREF = V

/ 2

MIXOUT

LIMIN

VREF

CZ CZ

IF BPF

LIMOUT

RSSI

LIMOUT

RSSI

RXIN

LO LO

POWER

MANAGEMENT

TXOUT

0°

LO PHASE SHIFTER

90°

LIMITER

TRANSMIT VGA/PA

VGA

MAX2510

OFFSET

CORRECTION

RXEN

TXEN

Figure 1. Functional Diagram

Page 10

MAX2510

Received Signal-Strength Indicator

The RSSI output provides a linear indication of the received power level on the LIMIN input. The RSSI monotonic dynamic range exceeds 90dB while providing better than 80dB linear range. The RSSI output pulses current into a 330pF (typical) external filter capacitor. The output is internally terminated to ground with 11kΩ, and this R-C time constant sets the decay time. The rise time is limited by the RSSI pin’s output drive current. The rise time is typically less than 100ns with no capacitor connected. Larger capacitor values slow the rise time.

Transmitter

The I, I and Q, Q baseband signals are input to a pair of double-balanced mixers, which are driven from a quadrature LO source. The quadrature LO is generated on-chip from the oscillator input present at the LO and LO pins. The two mixers’ outputs are summed. With quadrature baseband inputs at the I, I and Q, Q pins, the unwanted sideband is largely canceled. The resulting signal from the mixers is fed through a variable-gain amplifier (VGA) with more than 40dB of gain-adjust range.

The VGA output is connected to a driver amplifier with an output 1dB compression point of +2dBm. The output power can be adjusted from approximately +2dBm to -40dBm by controlling the GC pin. The resulting signal appears as a differential output on the TXOUT and TXOUT pins.

TXOUT and TXOUT are open-collector outputs and need external pull-up inductors to VCCfor proper operation, as well as a DC block so the load does not affect DC biasing. A shunt resistor across TXOUT and TXOUT (100Ω typical) can be used to back terminate an external filter, as shown in the

Typical Operating Circuit

. Alternatively, a single-ended load can be connected to TXOUT, as long as TXOUT is tied directly to VCC. Refer to the

Applications Information

section for details.

Local-Oscillator Inputs

The MAX2510 requires an external LO source for the mixers. LO and LO are high-impedance inputs (>1kΩ). The external LO signal is buffered internally and fed to both the receive mixer and the LO phase shifter used for the transmit mixers.

In a typical application, externally terminate the LO source with a 50Ω resistor and then AC couple into LO. Typically, the LO power range should be -13dBm to

0dBm (into 50Ω). Connect a bypass capacitor from LO to ground. Alternatively, a differential LO source (externally terminated) can drive LO and LO through series coupling capacitors.

Power Management

To provide advanced system power management, the MAX2510 features four operating modes that are selected via the RXEN and TXEN pins, according to Table 1 (supply currents assume GC = 0.5V).

In shutdown mode, all part functions are off. Standby mode allows fastest enabling of either transmit or receive mode by keeping the VREF generator active. This avoids delays in stabilizing the limiter input circuitry and the offset correction loop. Transmit mode enables the LO buffer, LO phase shifter, upconverter mixer, transmit VGA, and transmit output driver amplifier. Receive mode enables the LO buffer, downconverter mixer, limiting amplifier, and RSSI functions.

__________Applications Information

RX Input Matching

The RXIN, RXIN port typically needs an impedance matching network for proper connection to external circuitry, such as a filter. See the

Typical Operating Circuit

for an example circuit topology. Note that the receiver input can be driven either single-ended or differentially.

The component values used in the matching network depend on the desired operating frequency as well as on filter impedance. The following table indicates the RXIN, RXIN single-ended input impedance (that is, the impedance looking into either RXIN or RXIN). The information in Table 2 is also plotted in the

Typical

Operating Characteristics

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

10 ______________________________________________________________________________________

High

Low

High

TXEN

STATE

Low

0.5m

14m

17m

TYPICAL

SUPPLY

CURRENT (A)

0.2µ

Standby

Receive

Transmit

MODE

Shutdown

High

Low

RXEN

STATE

Low

Table 1. Power-Supply Mode Selection

Page 11

Table 2. RXIN or RXIN Input Impedance

Receive IF Filter

The interstage filter, located between the MIXOUT pin and the LIMIN pin, is typically a three-terminal, 330Ω,

10.7MHz bandpass filter. This filter prevents the limiter from acting on any undesired signals that are present at the mixer’s output, such as LO feedthrough, out-ofband channel leakage, and spurious mixer products. The filter connections are also set up to feed DC bias from VREF into LIMIN and MIXOUT through two 330Ω filter-termination resistors. (See the

Typical Operating

Circuit

for more information).

Transmit Output Matching

The transmit outputs, TXOUT and TXOUT, are opencollector outputs and therefore present a high impedance.

For differential drive, TXOUT and TXOUT are connected to V

via chokes, and each side is AC coupled to the load. A terminating resistor between TXOUT and TXOUT sets the output impedance. This resistor provides a stable means of matching to the load.

TXOUT and TXOUT are voltage-swing limited, and therefore cannot drive the specified maximum power across more than 150Ω load impedance. This load impedance typically consists of a shunt-terminating resistor in parallel with a filter load impedance. To drive higher output load impedances, the gain must be reduced (via the GC pin) to avoid saturating the TX output stage.

For single-ended applications, connect the unused TX output output pin directly to VCC.

400MHz ISM Applications

The MAX2510 can be used as a front-end IC in applications where the RF carrier frequency is in the 400MHz ISM band. In this case, Maxim recommends preceding the MAX2510 receiver section with a low-

noise amplifier (LNA) that can operate over the same supply voltage range. The MAX2630–MAX2633 family of amplifiers meets this requirement. In many applications, the MAX2510’s transmit output power is sufficient to eliminate the need for an external power amplifier.

______________________Layout Issues

A well-designed PC board is an essential part of an RF circuit. Use the MAX2510 evaluation kit and the recommendations below as guides to generate your own layout.

Power-Supply Layout

A star topology, which has a heavily decoupled central VCCnode, is the ideal power-supply layout for minimizing coupling between different sections of the chip. The VCCtraces branch out from this node, each going to one VCCconnection in the MAX2510 typical operating circuit. At the end of each of these traces is a bypass capacitor that presents low impedance at the RF frequency of interest. This method provides local decoupling at each VCCpin. At high frequencies, any signal leaking out of a supply pin sees a relatively high impedance (formed by the VCCtrace impedance) to the central VCCnode, and an even higher impedance to any other supply pin, minimizing Vcc supply-pin coupling.

A single ground plane suffices. Where possible, multiple parallel vias aid in reducing inductance to the ground plane.

Place the VREF decoupling capacitor (0.1µF typical) as close to the MAX2510 as possible for best interstage filter performance. For best results, use a high-quality, low-ESR capacitor.

Matching/biasing networks around the receive and transmit pins should be symmetric and as close to the chip as possible. A cutout in the ground plane under the matching network components can be used to reduce parasitic capacitance.

Decouple pins 19 and 21 (VCC) directly to pin 20 (Rx, Tx ground), which should be directly connected the ground plane. Similarly, decouple pin 8 directly to pin 7. Refer to the

Pin Description

table for more information.

MAX2510

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

______________________________________________________________________________________ 11

64 - j109

94 - j143

149 - j184

SERIES IMPEDANCE

(Ω)

275 - j203

400

300

200

FREQUENCY

(MHz)

100

53 - j87500

Page 12

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

12 ______________________________________________________________________________________

Typical Operating Circuit

MAX2510

100pF

220nH

0.001µF

100Ω

10pF

330pF

TX OUTPUT (TO FILTER)

TXOUT

FOR SINGLE-ENDED

TX OPERATION

FOR SINGLE-ENDED

RX OPERATION

RXIN

GND

1282

GND

330Ω

BYPASS

FILTER

330Ω

MIXOUT

LIMIN

VREF CZ

LIMOUT

RXEN

CONTROL LOGIC

RECEIVE IF OUTPUT

BASEBAND Q INPUT

BASEBAND I INPUT

TXEN

CC LO

GND

LOIN

GND

RSSI

9 10

5 4

330pF

0.001µF

5OΩ

0.001µF

47pF

RSSI OUTPUT

GAIN CONTROL

FROM LOCAL OSCILLATOR

TXOUT

0.001µF 0.001µF

0.1µF

0.01µF

10.7MHz

BpF, Z

= 330Ω

MATCH