Features
•
All Functions and Channel Selections are Controlled by Serial Bus
RF Part
•
•
•
•
All Oscillators and PLL Integrated
IF Converter
FM Demodulator
RSSI
Low Frequency Part
•
•
•
•
•
Asymmetrical Input of Microphone Amplifier
Asymmetrical Output of Earpiece Amplifier
Compander
Power Supply Management
Serial Bus
Single-chip
Cordless
Telephone IC
U3600BM
Application
•
CT0 Standard
•
Narrowband Voice and Data Transmitting/Receiving Systems
1. Description
The programmable single-chip multichannel cordless phone IC includes all necessary
low frequency parts such as microphone- and earphone amplifier, compander, power-
supply management as well as all RF parts such as IF converter, FM demodulator,
RSSI, oscillators and PLL. Several gains and mutes in transmit and receive direction
are controlled by the serial bus. The compander can be bypassed.
Rev. 4516D–CT0–10/05
Table 2-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Pin Description
Symbol
PCLO
RFOGND
RFO
RFOVB
AGND
VBIAS
VRF
MLF
LFGND
MODIN
VDD
VSS
D
C
DACO
OPOUT
OPIN
TXO
LIMIN
COUT
CTC
COIN
MICO
MIC
DAIN
RXO
RECO2
RECO1
EXIN
ETC
IFIN2
IFIN1
MIX2IN
MIX2GND
MIX2O
VAF
XCK
OSCGND
MIX1O
MIX1IN1
MIX1IN2
GNDLO
LO2
LO1
Function
Phase comparator local oscillator
RF transmit output ground
RF transmit output
Power supply input of RF transmit output buffer
Analog ground for RF part
Decoupling capacitor of current reference
Supply voltage for RF part
Modulator loop filter
Modulator loop filter ground
Modulator input
Supply voltage output for peripherals and internal supply of digital part
Ground for LF analog and digital
Data input of serial bus
Clock input of serial bus
D/A and data comparator output
Operational amplifier output
Operational amplifier input (inverting)
Output of limiter amplifier
Limiter input
Compressor output
Compressor time constant control analog output
Compressor input
Microphone amplifier output
Inverting input of microphone amplifier
Data comparator input
Output of demodulator
Symmetrical output of receive amplifier
Expander input
Expander time constant control analog output
Symmetrical input of IF amplifier
Input of Mixer2
IF amplifier and Mixer2 ground
Mixer2 output
Supply voltage for AF/IF parts
Crystal oscillator input 11.15 MHz
Oscillator ground
Output of Mixer1
Symmetrical input of MIxer1
Ground of LO
Tank elements for LO are connected to these pins
4
U3600BM
4516D–CT0–10/05
U3600BM
3. System Description
Radio frequency IC for analog cordless telephone application in 26/50 MHz band (CTO stan-
dard). The IC performs full duplex communication. The transmitting and receiving frequency are
depending on whether the IC is used in the handset or in the base station.
Frequency converter comprise an FM transmitter with switchable output power and first receiver
mixer in the same unit. A two-wire bus interface can be used for the frequency control as well as
for switching the transmitter power amplifier and the receiver. Fine frequency adjust of reference
quartz oscillator is programmable.
The receive part is designed for a double conversion architecture. The incoming radio frequency
signal will be filtered and amplified before reaching the first mixer. At this stage the RF signal will
be converted down to the first intermediate frequency (10.7 MHz) by using a crystal oscillator
(LO1).
The transmit part contains two PLL controlled VCOs. The frequency modulation is accomplished
by super-posing the incoming audio signal on the PLL control voltage. Final frequency is a prod-
uct of mixing VCO1 with first local oscillator of receiver part (VCO3). The FM modulated carrier
is amplified by externals power amplifier before entering the output filter and the antenna
connector.
3.1
Adjustments for VCO1 and VCO2
To be able to use a wide frequency range for the VCOs (i.e., VCO2 26.3 MHz to 49.9 MHz) the
two internal VCOs (VCO1 and VCO2, i.e., the VCOs of the transmit part) have a rough adjust
and a fine adjust to increase the frequency range given by the phase comparator.
The rough adjusts for these VCOs are correlated with the country setting. For every country
there are two sets of VCO rough adjust settings, one for the base and one for the handset. See
tables at channels frequencies and dividers.
To compensate the variation in production there is a fine adjust for each of the VCOs. The fine
adjusts of the internal VCOs could be set manually (for test purposes) or set by the automatic
mode. Theoretically the sign of the changing (increase/ decrease when the voltage of the phase
comparator is to high) is selectable, but we need value 1 () in all cases.
Setting VCO1 (VCO2) under normal conditions:
EAFA1 (EAFA2) = 1, automatic fine adjust VCO1(VCO2) enabled
SAFA1 (SAFA2) = 1, sign of auto fine adjustment of VCO1 (VCO2) = 1.
3.2
Adjustment for VCO3
In order to increase the adjustment range of VCO3 with fixed external tank elements and/or for
“band switching”, especially for US frequencies, VCO3 has programmable capacitors inside.
These capacitors can be added by serial bus (FA3 [4:0]) between LO1 and LO2. There are 31
steps available, every step adding a capacitor of 0.5 pF.
5
4516D–CT0–10/05
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