900MHz Image-Reject Transceivers

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9

Pin Description (continued)

Ground Connection for VCO and Phase Shifters

26

GND

Ground (substrate)

27

GND

Ground Connection for Master Bias Cell

28

GND

Supply-Voltage Input for VCO and Phase Shifters. Bypass with a 47pF low-inductance capacitor to GND

(pin 26 if possible).

23

Supply-Voltage Input for Prescaler. Bypass with a 47pF low-inductance capacitor and 0.01µF to GND

(pin 20 if possible).

22

FUNCTION

PIN

NAME

Differential Oscillator Tank Port. See Applications Information for information on tank circuits or on using

an external oscillator.

25

Differential Oscillator Tank Port. See Applications Information for information on tank circuits or on using

an external oscillator.

24

TANK

TANK

17

16

15

18

19

21

1000pF

TRANSMIT IF INPUT (330

Ω)

VARACTOR:

ALPHA SMV1299-004

OR EQUIVALENT

RECEIVE IF OUTPUT (330

Ω)

SEE APPLICATIONS INFORMATION SECTION

L3: COILCRAFT 0805HS-060TJBC

COILCRAFT 0805HS-030TJBC

27

23

26

3

12

20

22

1

28

RECEIVE

RF INPUT

TRANSMIT

RF OUTPUT

5

9

7

6

0.01

µF

0.01

µF

47pF

0.1

µF

2

47pF

0.1

µF

8.2nH

12nH

22nH

18nH

47pF

47pF

47pF

8

11

0.01

µF

47pF

0.01

µF

MAX2420

MAX2421

MAX2422

MAX2460

MAX2463

6.8

3.3

3.3

6.8

6.8

L3

(nH)

PART

VCO TANK COMPONENTS FOR

915MHz TYPICAL RF

C26

(pF)

C2, C3

(pF)

1.8

3.6

3.0

1.5

2.4

3.3

4.0

4.0

4.0

4.7

R6, R7

(

Ω)

10

15

20

15

15

47pF

47pF

14

0.01

µF

47pF

RXIN

TXOUT

GND

GND

CAP2

GND

CAP1

TXON

RXON

VCOON

DIV1

MOD

PREOUT

TXON

RXON

VCOON

DIV1

MOD

TO PLL

GND

RXOUT

TXIN

100nH

GND

PREGND

47pF

24

25

VCO

ADJUST

C3

1k

Ω

47k

Ω

47pF

1k

Ω

C2

R6

R7

L3

C26

TANK

TXGAIN

LNAGAIN

TXGAIN

LNAGAIN

10

4

MAX2420

MAX2421

MAX2422

MAX2460

MAX2463

TANK

Figure 1. Typical Operating Circuit