A broadband HBT MMIC IQ modulator and millimeter-wave vector signal characterization

A broadband 50-110 GHz HBT MMIC IQ modulator and a vector signal measurement system for millimeter-wave applications are reported in this paper. For the digital modulation measurement, a QPSK modulation format was used with a 2-Mbps data rate for the IQ modulation. Using the 50-110 GHz vector signal measurement system, this MMIC chip shows an error vector magnitude (EVM) of within 12 % rms and a carrier rejection of more than 21 dB. The 110-GHz operation frequency of this MMIC is the highest among all the reported HBT vector modulators. Also, this is the first time the EVM test was performed for an IQ modulator at V-band and W-band. This MMIC is suitable for software defined radio (SDR), linearization techniques of power amplifier and related transmitter applications both in V-band and W-band.