Rainbow Electronics MAX2442 User Manual

General Description

The MAX2440/MAX2441/MAX2442 highly integrated
front-end receiver ICs provide the lowest cost solution for
cordless phones and ISM-band radios operating in the
900MHz band. All devices incorporate receive image­reject mixers to reduce filter cost. They operate with a
+2.7V to +4.8V power supply, allowing direct connection
to a 3-cell battery stack.

The signal path incorporates an adjustable-gain LNA
and an image-reject downconverter with 35dB image
suppression. These features yield excellent combined
downconverter noise figure (4dB) and high linearity with
an input third-order intercept point (IP3) of up to +2dBm.

All devices include an on-chip local oscillator (LO),
requiring only an external varactor-tuned LC tank for
operation. The integrated divide-by-64/65 dual-modulus
prescaler can also be set to a direct mode, in which it
acts as an LO buffer amplifier. Three separate power­down inputs can be used for system power manage­ment, including a 0.5µA shutdown mode. These parts
are compatible with commonly used modulation
schemes such as FSK, BPSK, and QPSK, as well as fre­quency hopping and direct sequence spread-spectrum
systems. All devices come in a 28-pin SSOP package.

Evaluation kits are available for the MAX2420/
MAX2421/MAX2422. The MAX2420/MAX2421/MAX2422
are transceivers whose receive sections and pinout are
identical to the MAX2440/MAX2441/MAX2442.

For complete transceiver devices, refer to the MAX2420/
MAX2421/MAX2422/MAX2460/MAX2463 and MAX2424/
MAX2426 data sheets.

________________________Applications

Cordless Phones Spread-Spectrum Communications

Wireless Telemetry Two-Way Paging

Wireless Networks

Features

♦ Receive Mixer with 35dB Image Rejection

♦ Adjustable-Gain LNA

♦ Up to +2dBm Combined Receiver Input IP3

♦ 4dB Combined Receiver Noise Figure

♦ Low Current Consumption:

23mA Receive

9.5mA Oscillator

♦ 0.5µA Shutdown Mode

♦ Operates from Single +2.7V to +4.8V Supply

MAX2440/MAX2441/MAX2442

900MHz Image-Reject Receivers

________________________________________________________________ Maxim Integrated Products 1

___________________Pin Configuration

19-1352; Rev 2; 12/00

PART

MAX2440EAI

MAX2441EAI

MAX2442EAI

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

28 SSOP

28 SSOP

28 SSOP

_______________Ordering Information

Functional Diagram appears at end of data sheet.

High side

INJECTION

TYPE

fRF+ 10.7

LO FREQ

(MHz)

High side

High side

fRF+ 70

fRF+ 46

MAX2442

MAX2441

70

46

MAX2440

PART

10.7

IF FREQ

(MHz)

______________________Selector Guide

EVALU

A

TIO

N

K

IT

A

V

AILA

BLE

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

TOP VIEW

V

CAP1

RXOUT

GND

RXIN

V

GND

GND

GND

LNAGAIN

V

GND

GND

GND

1

CC

2

3

4

5

MAX2440

6

CC

CC

MAX2441
MAX2442

7

8

9

10

11

12

13

14

SSOP

28

27

26

25

24

23

22

21

20

19

18

17

16

15

GND

GND

GND

TANK

TANK

V

CC

V

CC

PREOUT

PREGND

MOD

DIV1

VCOON

RXON

GND

MAX2440/MAX2441/MAX2442

900MHz Image-Reject Receivers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +4.8V, no RF signals applied, LNAGAIN = unconnected, V

VCOON

= 2.4V, V

RXON

= V

MOD

= V

DIV1

= 0.45V, PREGND

= GND, T

A

= T

MIN

to T

MAX

. Typical values are at TA= +25°C, VCC= +3.3V, 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.

Note 1: ≥25°C guaranteed by production test, <25°C guaranteed through correlation to worst-case temperature testing.
Note 2: Calculated by measuring the combined oscillator and prescaler supply current and subtracting the oscillator supply current.
Note 3: Calculated by measuring the combined oscillator and LO buffer supply current and subtracting the oscillator supply current.
Note 4: Calculated by measuring the combined receive and oscillator supply current and subtracting the oscillator supply current.

With LNAGAIN = GND, the supply current drops by 4.5mA.

V

CC

to GND...........................................................-0.3V to +5.5V

Voltage on LNAGAIN, RXON, VCOON,

DIV1, MOD .............................................-0.3V to (V

CC

+ 0.3V)

RXIN Input Power..............................................................10dBm

TANK, TANK Input Power ...................................................2dBm

Continuous Power Dissipation (T

A

= +70°C)

SSOP (derate 9.50mW/°C above +70°C) ....................762mW

Operating Temperature Range

MAX244_EAI...................................................-40°C to +85°C

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

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

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

PARAMETER

MIN TYP MAX UNITS

Receive Supply Current 23 36 mA

Prescaler Supply Current
(buffer mode)

5.4 8.5 mA

Oscillator Supply Current

Supply-Voltage Range 2.7 4.8 V

9.5 14 mA

Prescaler Supply Current
(divide-by-64/65 mode)

4.2 6 mA

CONDITIONS

V

RXON

= 2.4V, PREGND = unconnected (Note 4)

V

DIV1

= 2.4V (Note 3)

PREGND = unconnected

(Note 2)

Digital Input Voltage Low 0.45 V

0.5

RXON, DIV1, VCOON, MOD

VCOON = RXON = MOD =
DIV1 = GND

Digital Input Current ±1 ±10 µAVoltage on any one digital input = VCCor GND

Digital Input Voltage High V2.4RXON, DIV1, VCOON, MOD

Shutdown Supply Current

10

µA

TA= +25°C

TA= T

MIN

to T

MAX

AC ELECTRICAL CHARACTERISTICS

(MAX242X/MAX246X EV kit, VCC= +3.3V; fLO= 925.7MHz (MAX2440), fLO= 961MHz (MAX2441), fLO= 985MHz (MAX2442),
f

RXIN

= 915MHz; P

RXIN

= -35dBm; V

LNAGAIN

= 2V; V

VCOON

= V

RXON

= 2.4V; RXON = MOD = DIV1 = PREGND = GND; TA= +25°C,

unless otherwise noted.)

MAX2440/MAX2441/MAX2442

900MHz Image-Reject Receivers

_______________________________________________________________________________________ 3

CONDITIONS UNITSMIN TYP MAXPARAMETER

MHz800 1000

36 46 55

8.5 10.7 12.5

MHz

20 22 24.5

dB

26 35Image Frequency Rejection

55 70 85

19.5 25

12

19 21 23.5

(Note 7)

-16

(Notes 5, 8) dBm

-8

Input Third-Order Intercept

-19 -17

(Note 9) ns500Receiver Turn-On Time

Receiver on or off dBm-60LO to RXIN Leakage

V

LNAGAIN

= 1V

dBm

-18

Input 1dB Compression

LNAGAIN = V

CC

-26

18 24

LNAGAIN = VCC,
T

A

= T

MIN

to T

MAX

(Note 5)

45

dB

12

Noise Figure

dB

IF Frequency Range

(Notes 5, 6)

(Notes 5, 6)

Input Frequency Range

Conversion Power Gain

DIV1 = V

CC

(Notes 5, 7)

MAX2441

MAX2442

LNAGAIN = V

CC

V

LNAGAIN

= 1V

V

LNAGAIN

= 1V

LNAGAIN = V

CC

MAX2442

V

LNAGAIN

= 1V

LNAGAIN = GND

MAX2440

LNAGAIN = VCC,
T

A

= +25°C

MAX2440/MAX2441

MAX2440/MAX2441

MAX2442

RECEIVER

MAX2440/MAX2441/MAX2442

900MHz Image-Reject Receivers

4 _______________________________________________________________________________________

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX242X/MAX246X EV kit, VCC= +3.3V; fLO= 925.7MHz (MAX2440), fLO= 961MHz (MAX2441), fLO= 985MHz (MAX2442),
f

RXIN

= 915MHz; P

RXIN

= -35dBm; V

LNAGAIN

= 2V; V

VCOON

= V

RXON

= 2.4V; RXON = MOD = DIV1 = PREGND = GND; TA= +25°C,

unless otherwise noted.)

Oscillator Phase Noise

Oscillator Frequency Range 690 1100 MHz

82 dBc/Hz

8

(Notes 5, 10)

10kHz offset (Note 11)

Standby to RX

Note 5: Guaranteed by design and characterization.
Note 6: Image rejection typically falls to 30dBc at the frequency extremes.
Note 7: Refer to the Typical Operating Characteristics for plots showing receiver gain versus LNAGAIN voltage, input IP3 versus

LNAGAIN voltage, and noise figure versus LNAGAIN voltage.

Note 8: Two tones at P

RXIN

= -45dBm each, f1 = 915.0MHz and f2 = 915.2MHz.

Note 9: Time delay from RXON = 0.45V to RXON = 2.4V transition to the time the output envelope reaches 90% of its final value.
Note 10: Refers to useable operating range. Tuning range of any given tank circuit design is typically much narrower (refer to Figure 1).
Note 11: Using tank components L3 = 5.0nH (Coilcraft A02T), C2 = C3 = C26 = 3.3pF, R6 = R7 = 10Ω.
Note 12: This approximates a typical application in which a transmitter is followed by an external PA and a T/R switch with finite

isolation.

Note 13: Relative to the rising edge of PREOUT.

Prescaler Output Level

500 mVp-p

-11 -8

Required Modulus Setup Time 10 ns

ZL= 100kΩ

| |

10pF

Divide-by-64/65 mode (Notes 5, 13)

Standby mode with P

RXIN

= -45dBm to

P

RXIN

= 0dBm (Note 12)

70

Oscillator Buffer Output Level

-12

dBm

Oscillator Pulling kHz

PARAMETER MIN TYP MAX UNITSCONDITIONS

TA= T

MIN

to T

MAX

TA= +25°C

DIV1 = 2.4V, ZL= 50Ω

(Note 5)

OSCILLATOR AND PRESCALER