Philips Semiconductors

Product specification

SA9502

Dual-band, CDMA/AMPS downconverter IC

1999 Mar 19

4

PIN CONFIGURATION

1

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

FM IF

FM IFB

GND

PCS RF

PCS RFB

PCS/CEL SEL

PWR ON/OFF

CEL RF

GND

CDMA IF

CDMA IFB

GND

CDMA/FM SEL

CEL LO IN

GND

PCS LO

GND

LO BUFFER ENABLE

LO OUT

10

SR01760

Figure 2.

Pin Configuration

PIN DESCRIPTION

PIN

SYMBOL

DESCRIPTION

1

FM IF

Non-inverting FM IF output

2

FM IFB

Inverting FM IF output

3

GND

Analog ground

4

PCS RF

non-inverting PCS RF input

5

PCS RFB

Inverting PCS RF input

6

PCS/CEL SEL

PCS and cellular band select

7

PWR ON/OFF

Power enable

8

CEL RF

Cellular RF input

9

GND

Ground

10

Power supply

11

LO OUT

LO output to synthesizer

12

GND

Ground

13

LO BUFFER

ENABLE

Logic signal which switches the LO

buffer output ON or OFF

14

PCS LO

PCS mixer direct LO input

15

GND

Ground

16

CEL LO

Cellular LO input

17

CDMA/FM SEL

CDMA and FM mode select in cellular

band; LO direct or via frequency

doubler in PCS mode

18

GND

Ground

19

CDMA IFB

Inverting CDMA IF output

20

CDMA IF

Non-inverting CDMA IF output

FUNCTIONAL DESCRIPTION

Mode Selection Logic

The SA9502 downconverter IC has several modes of operation for

which the selection logic is summarized in Table 1 and defined in

detail in Table 2. Different mode selections require different portions

of the circuit to be active. It should be noted that only the states

specified in Table 2 are valid selections for operation.

Local Oscillator Section

Local oscillator drive for the mixers is provided through single ended

inputs on either pin 16 (CEL LO) or pin 14 (PCS LO). The LO signal

has to be AC-coupled into the circuit and needs to be externally

matched. Inside the circuit, the cellular band LO signal is amplified

and buffered to drive: Either the cellular CDMA mixer or FM mixer

or the frequency doubler for the PCS mixer LO and additionally the

LO output buffer. The mode selection summary in Table 1 shows the

logic to apply to pins 6 and 17 to choose one of four possible

modes. The LO output buffer can be programmed on or off via LO

Buffer Enable (Pin 13). The LO output buffer’s frequency is the

same as that used by the mixers.

Cellular and PCS Mixers

The SA9502 has one single ended cellular band RF input which

feeds either the cellular CDMA mixer or the cellular FM mixer

circuits. Each mixer is optimized to meet cellular band CDMA or

analog FM requirements. The cellular FM mixer has its own

dedicated differential output on pins 1 and 2 which should to be

externally matched to the FM IF SAW filter. The cellular CDMA

mixer shares the same output pins with the CDMA PCS mixer.

Selection between these two mixers is via pin 6 (PCS/CEL) and as

the two mixers are never on at the same time, it allows a common

CDMA SAW filter to be used for both bands. The CDMA PCS mixer

has a differential RF input which should be used with an external

balun matching circuit. To avoid upsetting the internal biasing, the

RF inputs at both cellular and PCS band mixers should be

AC-coupled in. The CDMA and FM IF mixer outputs are of the open

with external tuning inductors which can also serve in the matching

of the IF SAW filter.