A single chip direct conversion CMOS transceiver for quad-band GSM/GPRS/EDGE and WLAN with integrated VCO´s and fractional-N synthesizer

This paper presents the first WWAN + WLAN integrated radio transceiver. The 0.18 μm CMOS chip includes a fully integrated receiver, transmitter and frequency synthesizer. The device includes a direct conversion receiver that converts the RF signal to quadrature analog baseband while yielding a high IIP2 (> +45.0 dBm) and low LO radiation (<-100 dBm over all bands). The receiver includes selectable baseband filters and variable gain amplifiers. The transmitter uses a quadrature direct modulator and pre-power amplifiers; that can support low gain GSM PAs with low carrier leakage (<-40 dB). An RF ΣΔ fractional-N synthesizer is integrated on-chip to generate the system local oscillator signal. A flexible baseband interface is provided to allow for control via two distinct baseband processor systems.