Philips Semiconductors
Product specification
Dual-band, CDMA/AMPS downconverter IC
SA9502
PIN CONFIGURATION
FM IF
FM IFB
GND
PCS RF
PCS RFB
PCS/CEL SEL
PWR ON/OFF
CEL RF
GND
1
2
3
4
5
6
7
8
9
20 CDMA IF
19 CDMA IFB
18 GND
17 CDMA/FM SEL
16 CEL LO IN
15 GND
14 PCS LO
13 LO BUFFER ENABLE
12 GND
11 LO OUT
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.
V
CC
10
SR01760
Figure 2. Pin Configuration
PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
SYMBOL
FM IF
FM IFB
GND
PCS RF
PCS RFB
PCS/CEL SEL
PWR ON/OFF
CEL RF
GND
V
CC
LO OUT
GND
LO BUFFER
ENABLE
PCS LO
GND
CEL LO
CDMA/FM SEL
DESCRIPTION
Non-inverting FM IF output
Inverting FM IF output
Analog ground
non-inverting PCS RF input
Inverting PCS RF input
PCS and cellular band select
Power enable
Cellular RF input
Ground
Power supply
LO output to synthesizer
Ground
Logic signal which switches the LO
buffer output ON or OFF
PCS mixer direct LO input
Ground
Cellular LO input
CDMA and FM mode select in cellular
band; LO direct or via frequency
doubler in PCS mode
Ground
Inverting CDMA IF output
Non-inverting CDMA IF output
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
collector type. So, they should be biased to the supply voltage V
CC
with external tuning inductors which can also serve in the matching
of the IF SAW filter.
18
19
20
GND
CDMA IFB
CDMA IF
1999 Mar 19
4
PHILIPS [ NXP SEMICONDUCTORS ]
