User Guide

Nokia Customer Care System Module
Company Confidential RH-21
Issue 2 07/2004  2004 Nokia Corporation. Page 41
Regulators
The regulator circuit is the UEM and the specifications can be found in the table below:
Receiver
The receiver shows a superheterodyne structure with zero 2nd IF. Lowband and highband
receivers have separate frontends from the diplexer to the first IF. Most of the receiver
functions are integrated in the RF ASIC. The only functions out of the chip are highband
LNA, duplexers, and SAW filters. In spite of a slightly different component selection, the
receiver characteristics are very similar on both bands.
An active 1st downconverter sets naturally high gain requirements for preceding stages.
Hence, losses in very selective frontend filters are minimized down to the limits set by
filter technologies used and component sizes. LNA gain is set up to 16dB, which is close
to the maximum available stable gain from a single stage amplifier. LNAs are not exactly
noise matched in order to keep passband gain ripple in minimum. Filters have relative
tight stopband requirements, which are not all set by the system requirements but the
interference free operation in the field. In this receiver structure, linearity lies heavily on
mixer design. The 2nd order distortion requirements of the mixer are set by the 'half IF'
suppression. A fully balanced mixer topology is required. Additionally, the receiver 3rd
order IIP tends to depend on active mixer IIP3 linearity due to pretty high LNA gain.
The IF stages include a narrowband SAW filter on the 1st IF and a integrated lowpass fil-
tering on zero IF. The SAW filter guarantees 14dBc attenuation at alternating channels,
which gives acceptable receiver IMD performance with only moderate VHF local phase
noise performance. The local signal's partition to receiver selectivity and IMD depends
then mainly on the spectral purity of the 1st local. Zero 2nd IF stages include most of
the receivers signal gain, AGC control range, and channel filtering.
Regulator
name
Output voltage (V)
Regulator Max.
current (mA)
RF total
1GHz
RF total 2GHz
VR1 a/b 4.75 ± 3% 10 4 4
VR2 2.78 ± 3% 100 100 76
VR3 2.78 ± 3% 20 2 2
VR4 2.78 ± 3% 50 23 24
VR5 2.78 ± 3% 50 5 5
VR6 2.78 ± 3% 50 5 5
VR7 2.78 ± 3% 45 40 45
IPA1, IPA2 2.7 max. 1 ± 10%
3 ± 4%
3.5 ± 4%
5 ± 3%
1.3 – 5.0 1.3 – 3.7
VREFRF01 1.35 ± 0.5% 0.12 0.05 0.05
VFLASH1 2.78 ± 3% 70 1 1