3 to 5-GHz Si-Bipolar Quadrature Modulator and Demodulator Using a Wideband Frequency-Doubling Phase Shifter


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A    No.2    pp.506-512
Publication Date: 2001/02/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques Supporting the System LSI Era)
Si bipolar,  quadrature modulator,  quadrature demodulator,  wireless LAN,  5-GHz band,  

Full Text: PDF>>
Buy this Article

A 3 to 5-GHz Si-bipolar quadrature modulator and demodulator are described. Both feature a wideband frequency-doubling 90-degree phase shifter that has a mechanism for self-correction of phase errors caused by an original 90-degree phase-shift network at the half frequency of the carrier. Therefore, the phase shifter produces accurate quadrature carrier signals with doubled frequency. The quadrature modulator and demodulator in 30-GHz Si bipolar technology dissipate 80 mA at a 3-V supply. Image rejection of the modulator is more than 40 dB between 3.2 to 5.2 GHz. The phase and amplitude errors of the demodulator are less than 1.5 degrees and less than 0.15 dB, respectively, between 3.5 to 5.2 GHz. Therefore, both are suitable for either direct conversion or image-rejection transceivers for 5-GHz applications.