Nokia 3510i Service Manual
CCS Technical Documentation
System Module & UI
RH-9
Issue 1 11/02
ãNokia Corporation
Page 79
Figure 29: Simplified Synthesizer
Receiver
The Receiver is a dual band, direct conversion, linear receiver. The received RF signal is
routed from the antenna to the RX/TX switch. The RX/TX switch performs both the
switching between receive – transmit routing of the antenna signals as well as the selec-
tion of the band to be used.
routed from the antenna to the RX/TX switch. The RX/TX switch performs both the
switching between receive – transmit routing of the antenna signals as well as the selec-
tion of the band to be used.
The RX signal is routed from the RX/TX switch to the RX bandpass filter. The filter input is
single ended and the output is balanced in order to exploit the balanced nature of the
RF-ASIC. The band limited signal is amplified in the internal LNA and the Pre-gain ampli-
fier before being converted to a BB signal in the passive mixer.
single ended and the output is balanced in order to exploit the balanced nature of the
RF-ASIC. The band limited signal is amplified in the internal LNA and the Pre-gain ampli-
fier before being converted to a BB signal in the passive mixer.
Figure 30: Simplified Mjoelner BB, either I or Q channel
The BB signal from the passive mixer is amplified by 24 dB in BBAMP1. In order to pro-
vide the first band limitation a 4 MHz pole is added at the input and a 250 kHz pole at
the output of BBAMP1. No AGC is provided in this amplifier. BBAMP1 is followed by LPF1
with a gain of 14 dB and with a pole at 86 kHz. LPF1 is followed by DCN1 (DC compen-
sation amplifier 1) with a minimum gain of 0 dB and a maximum gain of 24 dB. The
DCN1 output is followed by a controlled attenuator with a control range of 48 dB. The
attenuator output is filtered in LPF2, a biquad filter, before passing DNC2, (DC compen-
sation amplifier 1). The total filter combination gives a flat transfer function from DC to
90 kHz. The frequency characteristic of both LPF1 and LPF2 can be software adjusted to
compensate for process and temperature variations. All capacitors for both filters are
located in the RF-ASIC.
vide the first band limitation a 4 MHz pole is added at the input and a 250 kHz pole at
the output of BBAMP1. No AGC is provided in this amplifier. BBAMP1 is followed by LPF1
with a gain of 14 dB and with a pole at 86 kHz. LPF1 is followed by DCN1 (DC compen-
sation amplifier 1) with a minimum gain of 0 dB and a maximum gain of 24 dB. The
DCN1 output is followed by a controlled attenuator with a control range of 48 dB. The
attenuator output is filtered in LPF2, a biquad filter, before passing DNC2, (DC compen-
sation amplifier 1). The total filter combination gives a flat transfer function from DC to
90 kHz. The frequency characteristic of both LPF1 and LPF2 can be software adjusted to
compensate for process and temperature variations. All capacitors for both filters are
located in the RF-ASIC.
The gain characteristic of the BB amplifier is an amplifier with a maximum gain of 80 dB
with an AGC range of 72 dB.
with an AGC range of 72 dB.
VCO
CHARGE
PUMP
PHASE
DET.
M
R
f_out
LP
Kvco
Kd
f
ref
f_out /M
26 MHz frequency
reference
reference
AFC-controlled
VCTCXO
VCTCXO
4 MHz
pole at
pole at
input
250
kHz
kHz
pole at
output
86 kHz
pole
BBAMP
1
LPF 1
DCN 1
AGC
LPF 2
DCN 2
114 kHz
pole pair
Gain ~24 dB
Gain ~14 dB
Gain ~ 0 to
24 dB
Gain ~ -48
to 0 dB
Gain ~20 dB
Gain ~0 dB
AGC ~ 0 dB
AGC ~ 0 dB
AGC ~ 24 dB
AGC ~ 48 dB
AGC ~ 0 dB
AGC ~ 0 dB
Step ~ 6 dB
Step ~ 6 dB