Nokia 9000i, Service Manual

Page: 88 / 434

After Sales
Technical Documentation
RAE/RAK–1N
RF
Page 3– 22
Amendment 1 04/97
Power control circuitry
The power control loop consists of a power detector and a differential
control circuit. The power detector is a combination of a directional
coupler and a diode rectifier. The differential control circuit compares the
detected voltage and the control voltage (TXC) and controls voltage
controlled amplifier (in CRFRT) or the power amplifier. The control circuit
is a part of CRFRT.
Table 15. Power control specification
Parameter Minimum Typical /
Nominal Maximum Unit / Notes
Supply voltage
using CRFRT 4.5
4.27
4.7
4.5 4.9
4.73
V
V
Supply current
using CRFRT 3.0 5.0 mA
Power control range GSM
PCN 20
20 dB
dB
Power control inaccuracy
GSM
PCN +/–1.0
+/–1.0 dB
dB
Dynamic range GSM
PCN 80
80 dB
dB
Input control voltage range
GSM
PCN 0.1
0.1 2.8
2.8 V
Synthesizers
Reference oscillator
In GSM and PCN the reference oscillator is a discrete VCXO and the
frequency is 26 MHz. In PCN the buffer amplifier for the reference
oscillator is located in the RF side near the local oscillator, although it is
drawn in the baseband schematic.
The oscillator signal is used for a reference frequency of the synthesizers
and the clock source for the baseband circuits.
Table 16. VCXO specification
Parameter Minimum Typical /
Nominal Maximum Unit / Notes
Center frequency 26 MHz
Frequency tolerance ppm, Vc=2.2 V
Frequency control range 67 ppm
Supply voltage 4.6 4.7 4.8 V
Current consumption 1.5 1.7 mA