Receiver - Nokia RH-41 Series Technical Documentation Manual

RH-41
System Module
Regulator name
VR1 a/b
VR2
VR3
VR4
VR5
VR6
VR7
IPA1, IPA2
VREFRF01
VFLASH1

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.
IF stages include a narrowband SAW filter on the 1st IF and a integrated lowpass filter-
ing on zero IF. 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 receiv-
ers signal gain, AGC control range and channel filtering.
Page 44
Output voltage (V)
4.75 ± 3%
2.78 ± 3%
2.78 ± 3%
2.78 ± 3%
2.78 ± 3%
2.78 ± 3%
2.78 ± 3%
2.7 max.
1.35 ± 0.5%
2.78 ± 3%
Nokia Corporation
CCS Technical Documentation
Regulator Max.
RF total 1 GHz
current (mA)
10 4
100 100
20 2
50 23
50 5
50 5
45 40
1 ± 10% 1.3 – 5.0
3 ± 4%
3.5 ± 4%
5 ± 3%
0.12 0.05
70 1
Confidential
RF total 2 GHz
4
76
2
24
5
5
45
1.3 – 3.7
0.05
1
Issue 2 09/2003