A 4–10 GHz Programmable CMOS Vector-Sum Phase Shifter for a Two-Channel Transmitter

A 6-bit full-span programmable vector-sum phase shifter was presented in this brief. A transformer-based matching network is used to match the PPF-based I/Q generator to the variable gain amplifier-based vector-modulator (VGA-based VM), which eliminates the performance degradation due to impedance mismatch. The proposed phase shifter integrated in a two-channel transmitter was implemented in a 180-nm CMOS process. A program-assisted method was used to select the desired 6-bit (64) phase states from the total 4096 measured states of the chip, to realize a highly accurate phase tuning. The center frequency of the phase tuning can be set in the program, for different operation frequency points. An ultra-low root-mean-square (rms) phase/gain error less than 0.5°/0.15 dB are obtained at corresponding single frequency points. Moreover, a “band” mode is available as well, and rms phase/gain errors less than 2.25°/0.56 dB and 1.1°/0.32 dB are obtained at 4–10 GHz and 5.5-7.5 GHz, respectively.