General description
The SA58646 is a BiCMOS integrated circuit that performs all functions from the antenna to the microcontroller for reception and transmission for both the base station and the handset in a 902 MHz to 928 MHz full-duplex radio. The SA58646 may be used in a UHF push-to-talk walkie-talkie or in a UHF to 900 MHz data transceiver. The SA58646 is a pin-compatible derivative of the UAA3515 with advanced features.

FEATUREs
◾ RF RX (single frequency conversion FM receiver):
   ✦ Integrated LNA
   ✦ Image reject mixer
   ✦ FM detector at 10.7 MHz including an IF limiter, a wide band PLL demodulator, an output amplifier and a RSSI output
   ✦ Carrier detection with programmable threshold
   ✦ Programmable data amplifier (slicer) phase
◾ Synthesizer:
   ✦ Crystal reference oscillator with integrated tuning capacitor
   ✦ Reference frequency divider
   ✦ Narrow band RX PLL including RX VCO with integrated varicaps
   ✦ Narrow band TX PLL including TX VCO with integrated varicaps
   ✦ VCO external inductors can be done with printed transmission lines on the PCB which offers substantial savings
   ✦ Programmable clock divider with output buffer to drive a microcontroller
◾ Baseband RX section:
   ✦ Programmable RX gain (enable phone volume control)
   ✦ Expander with output noise level control
   ✦ Earpiece amplifier with volume control feature
   ✦ Data amplifier
◾ Baseband TX section:
   ✦ Microphone amplifier
   ✦ Compressor with automatic level control and hard limiter
   ✦ Programmable TX gain
◾ Microcontroller interface:
   ✦ 3-wire serial interface
◾ Other features:
   ✦ Voltage regulator to supply internal PLLs
   ✦ Selectable voltage doubler
   ✦ Programmable low battery detection time multiplexed with RSSI carrier detection

APPLICATIONs
◾ 902 MHz to 928 MHz full-duplex radio
◾ UHF to 900 MHz data transceiver
◾ UHF push-to-talk walkie-talkie