An Integrated 5?GHz Wideband Quadrature Modem for OFDM Gbit/s Transmission in SiGe:C BiCMOS

摘要

This paper presents a 5?GHz wideband I/Q modulator/demodulator for 650?MHz OFDM signal bandwidth, which is integrated with a 5?GHz phase locked loop for I/Q generation. The quadrature signals are derived from a 10?GHz CMOS VCO followed by a bipolar frequency divider. The phase noise at 1?MHz offset is?112?dBc/Hz for the modulator as well as for the demodulator. The chips were produced in a 0.25?μm SiGe BiCMOS technology. The signal-to-noise ratio (SNR) of transmitted/received OFDM signal and the corresponding I/Q mismatch versus baseband frequency are given. The modulator achieves an SNR of 22–23?dB, and the demodulator realizes an SNR up to 22?dB. The modulator reaches a data rate of 2.16?Gbit/s using 64?QAM OFDM, and the demodulator realizes 1.92?Gbits/s.