After Sales
Technical Documentation
RAE/RAK–1N
RF
Page 3– 18
Amendment 1 04/97
Transmitter
Table 10. RF Characteristics, Transmitter
Item GSM PCN
TX frequency range 890...915 MHz 1710...1785 MHz
Type Upconversion Upconversion
Intermediate frequency 116 MHz 200 MHz
Maximum output power 2 W (33 dBm) 1 W (30 dBm)
Gain control range 20 dB 20 dB
Maximum RMS phase error 5 deg. 5 deg.
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.
Table 11. CRFRT TX–part specifications
Parameter Minimum Typical /
Nominal
Maximum Unit / Notes
Supply voltage 4.27 4.5 4.73 V
Supply current 36 45 mA
Transmit Frequency Input Minimum Typical /
Nominal
Maximum Unit / Notes
LO input frequency 170 400 MHz
LO input level 0.2 Vpp
LO input resistance 70 100 130 ohm
LO input capacitance 4 pF
Modulator Inputs (I/Q) Minimum Typical /
Nominal
Maximum Unit / Notes
Input bias current (balanced) 100 nA
Input common mode voltage 2.0 2.2 2.4 V
Input level (balanced) 1.1 Vpp
Input frequency range 0 300 kHz
Input resistance (balanced) 200 kohms
Input capacitance (balanced) 4 pF
Output frequency 85 200 MHz
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