The HFA3683A is a monolithic SiGe half-duplex RF/IF transceiver designed to operate in the 2.4GHz ISM band. The receive chain features a low noise, gain selectable amplifier (LNA) followed by a down-converter mixer. An up-converter mixer and a high performance preamplifier compose the transmit chain. The remaining circuitry comprises a high frequency Phase Locked Loop (PLL) synthesizer with a three wire programmable interface for local oscillator applications.