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– 5-4 –
TX path is a translation loop architecture consisting of an IQ modulator, integrated high power VCO, offset mixer, programmable
divider, PFD, charge pump, and power amplifier with its control circuit.
The device consists of an In-phase and Quadrature (I/Q) modulator within a frequency translation loop designed to perform
frequency up-conversion with high output spectral purity.
The clock source is 26 MHz VCTCXO external instead of XTAL function block active.
The VCTCXO provides an external clock source
which
is more stable over extreme temperature conditions than an internal clock.
It has a power saving function in standby mode.
■
Transceiver - - Transmitter
Base-band
section
Antenna
3-wire bus
TX IN
TX IN I/Q
PAVAPC
VAPC
Band Select
PA
TXVCO
900
1800/1900
PFD
UHF synthesiser
UHF synthesiser
PA gain
controller
Figure 5.3. Transmitter block diagram