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This paper presents a SiGe BiCMOS transmitter for large bandwidth Polar Modulation and PWM signals. For flexibility, the transmitter presented in the paper has an externally controllable class of operation. Fabricated in a SiGe BiCMOS process (QUBIC4G), the measured saturated output power of the transmitter is 27dBm and the measured PAE is 62%. It features an IMD3 of -30dBc up to 25dBm peak envelope power and fulfills the spectral mask for WLAN 802.11.a signals.

An efficiency-enhanced power amplifier (PA) is analysed and designed for wide-bandwidth envelope elimination and restoration (EER) system with application to orthogonal frequency-division multiplexing (OFDM) wireless local area network (WLAN) system. The proposed PA has no bandwidth limitation as that of the DC-DC converter used in classical polar modulator. The simulation result shows that the average poweradded efficiency (PAE) is 25.38% at a 5.5Ghz average output power of 19dBm with peak to average ratio about 7.7dB and the overall error vector magnitude (EVM) remains less than 10% throughout its output power range. This PA shows much higher PAE among the reported WLAN BiCMOS HBT PAs as well as satisfying IEEE802.11a transmitter back off requirement.Index Terms-Envelope elimination and restoration (EER), orthogonal frequency-division multiplexing (OFDM), power amplifier (PA), EVM, WLAN, polar modulator.