A miniaturized MMIC analog phase shifter using two quarter-wave-length transmission lines

This paper describes a miniaturized monolithic-microwave integrated-circuit (MMIC) analog phase shifter using two quarter-wave-length transmission lines. A conventional analog phase shifter employs an analog phase-shifter topology using a 3-dB 90degrees branch-line hybrid requiring four quarter-wave-length transmission lines. Thus, in the first stage of our study, we present a new analog phase-shifter topology using only two quarter-wave-length transmission lines. The phase shifter here has only one-half as many transmission lines as a conventional analog phase shifter using a 3-dB 90degrees branch-line hybrid, and the circuit can be miniaturized to less than one-fourth as compared to the conventional analog phase shifter. Furthermore, we show that the operating frequency range of the phase shifter is very wide and can obtain large phase variation with small capacitance variation. Next, an experimental Ku-band MMIC analog phase shifter is presented. A phase shift of more than 180degrees and an insertion loss of 3.6 +/- 1.1 dB are obtained at the frequency range from 12 to 14 GHz. The chip size of the experimental MMIC phase shifter is less than 3.0 mm(2).