A low distortion C-band double balanced up-converter MMIC

We present the design and measurement of a low distortion C-band double balanced up-converter MMIC with an excellent LO rejection and image rejection performance implemented in 0.6 /spl mu/m GaAs MESFET processes. The upconverter MMIC consists of a double balanced diode ring mixer, a voltage controlled oscillator (VCO) with wide frequency tuning range performance, a buffer amplifier, an IF amplifier, and a RF amplifier. The upconverter MMIC integrated with a VCO exhibits an up-conversion gain of 7 dB and an IIP3 of 16 dBm as well as LO-to-RF rejection of 50 dB and image rejection of 11 dBc without any band pass filtering. These isolation performances are comparable to, or better than, the best reported results of double balanced mixers (DBM) implemented in GaAs-based technologies. In addition, a second harmonic suppression of more than 22 dB or more is obtained. This upconverter MMIC can be used for C-band wireless LAN applications from 5 GHz to 6 GHz due to its high linearity and wide-band operation.