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.

This IC integrates most of the functions required for a half-duplex or full-duplex radio in a

single integrated circuit. Additionally, the programmability implemented reduces

significantly external components count, board space requirements and external

adjustments.

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