A Delay Line Phase Shifter for Ultrawide-Band Operation

We present here results about a high-frequency analog phase shifter designed for multi-octave operation. Principles of this ultrawide-band phase shifter are based upon the use of a frequency tunable local oscillator (LO) which biases a pair of mixers (up- and down-converters); a delay line is inserted between the mixers. Through proper fequency variation, a phase-shifted intermediate frequency (IF) signal, resulting from fundamental mixing with the incident radio-frequency (RF) and the LO signal, is produced at the output of the delay line. The phase-shifted RF output signal is then obtained by down-conversion, using the same LO signal. Measurements done on a prototype indicate a 20:1 operational bandwidth.