A 5 GHz-band BiCMOS up/down-converter chip for GMSK modulation wireless systems

This multi-functional BiCMOS-based up/down-converter chip operating with a single bias voltage of 2.6-5.2 V developed for 5 GHz-band Gaussian minimum shift keying (GMSK) modulation wireless systems. To achieve these features, the following steps are taken: 1) To realize an independently optimum constant current source for each high-frequency circuit in the chip over a wide dc voltage, a distributed single power-supply arrangement is proposed. 2) To realize an attenuation feature without additional power dissipation and chip area, a low-noise attenuating amplifier concept is suggested. 3) To comply with the GMSK modulation requirement, a high-gain small phase variation limiting amplifier is incorporated. 4) To keep the phase noise and power consumption of the local oscillator (LO) low, a frequency doubling method is employed. The present chip can be combined with a GaAs power amplifier/antenna switch chip to provide a complete 5 GHz front-end system.