UAA3558

The UAA3558 BiCMOS device is a low power, highly integrated circuit. UAA3558 features a fully integrated receiver, from antenna filter output to the demodulated data output, an integrated VCO, a synthesizer to implement Bluetoothchannel frequencies, and a transmitter preamplifier to drive either the switch diode to antenna or a power amplifier.

The synthesizer's main divider UAA3558 is driven by the prescaler output in the range of 2400 to 2497 MHz and programmedvia a 3-wire serial bus. The reference divider ratio can be programmed to 12, 13, 16 or 26. Outputs ofthe main andreference dividers drive a phase comparator, where a charge pump produces phase error currentpulses forintegration UAA3558 in an external loop filter. The charge-pump current (phase comparator gain) is set to 3.5 mA.

The synthesizer UAA3558 is programmed and switches on 200 ms before the desired slot to lock the VCO to the requiredchannel frequency. Just before the desired slot, the synthesizer is switched off, allowing open loop modulation of the VCO during transmission.

The UAA3558 is designed to operate from 3.0 V nominal supplies. Separate power and ground pins of UAA3558 are provided tothe different parts of the circuit. The ground leads should be connected together externally to prevent large currentsflowing across the IC, which would cause damage. All VCC pins must also be at the same potential (VCC).