Transmitter; Modulator Circuit, Tx Part Of Crfrt - Nokia 9000i Service Manual

RAE/RAK–1N
RF

Transmitter

Item
TX frequency range
Type
Intermediate frequency
Maximum output power
Gain control range
Maximum RMS phase error

Modulator Circuit, TX part of CRFRT

The modulator is a quadrature modulator contained in Tx–section of
CRFRT IC. The I– and Q– inputs generated by RFI interface are
DC–coupled and fed via buffers to the modulator. The local signal is
divided by two to get accurate 90 degrees phase shifted signals to the I/Q
mixers. After mixing the signals are combined and amplified with
temperature compensated controlled gain amplifier (TCGA). Gain is
controlled with power control signal (TXC). The output of the TCGA is
amplified and the maximum output level is –10 dBm, typically.
Parameter
Supply voltage
Supply current
Transmit Frequency Input
LO input frequency
LO input level
LO input resistance
LO input capacitance
Modulator Inputs (I/Q)
Input bias current (balanced)
Input common mode voltage
Input level (balanced)
Input frequency range
Input resistance (balanced)
Input capacitance (balanced)
Output frequency
Page 3– 18
Table 10. RF Characteristics, Transmitter
890...915 MHz
Upconversion
2 W (33 dBm)
Table 11. CRFRT TX–part specifications
Minimum Typical /
Nominal
4.27 4.5
Minimum Typical /
Nominal
170
0.2
70 100
Minimum Typical /
Nominal
2.0 2.2
0
200
85
Technical Documentation
GSM
1710...1785 MHz
116 MHz
20 dB
5 deg.
Maximum
4.73
36 45
Maximum
400
130
4
Maximum
100
2.4
1.1
300
4
200
Amendment 1 04/97
After Sales
PCN
Upconversion
200 MHz
1 W (30 dBm)
20 dB
5 deg.
Unit / Notes
V
mA
Unit / Notes
MHz
Vpp
ohm
pF
Unit / Notes
nA
V
Vpp
kHz
kohms
pF
MHz