Michiaki Kasahara

An ultra-broad-band reflection-type phase-shifter MMIC with series and parallel LC circuits

An ultra-broad-band reflection-type phase shifter is proposed. Theoretically, the proposed phase shifter has frequency-independent characteristics in the case of 180/spl deg/ phase shift. The phase shifter is composed of a 3-dB hybrid coupler and a pair of novel reflective terminating circuits. The reflective terminating circuit switches two states of series and parallel LC circuits. Using an ideal circuit model without parasitic circuit elements, we have derived the determining condition of frequency independence of circuit elements. Extending the concept, we can also obtain a broad-band phase shifter for other phase difference as well. In this case, for a given phase difference and an operating frequency, we also derive a condition to obtain minimum variation of phase difference around the operating frequency. This enables the broad-band characteristics for arbitrary phase difference. The fabricated 180/spl deg/ reflective terminating circuit monolithic microwave integrated circuit (MMIC) has achieved a phase difference of 183/spl deg/ /spl plusmn/ 3 over 0.5-30 GHz. The 180/spl deg/ phase-shifter MMIC has demonstrated a phase shift of 187/spl deg/ /spl plusmn/ 7/spl deg/ over 0.5-20 GHz. The 90/spl deg/ reflective terminating circuit MMIC has performed a phase difference of 93/spl deg/ /spl plusmn/ 7/spl deg/ over 4-12 GHz.

A 6-18 GHz 5-Bit Phase Shifter MMIC Using Series/Parallel LC Circuit

A high performance 6-18 GHz 5-bit reflection type phase shifter MMIC is presented. It employs a novel ultra-broad-band circuit design technique utilizing a series/parallel LC circuit for an 180° phase shift over all frequencies. The fabricated phase shifter MMIC with SPDT switch suitable for T/R modules has demonstrated a typical insertion loss of 9.4 dB+/¿1.4 dB, a maximum RMS amplitude error of 0.33 dB and a maximum RMS phase error of 7° over entire operating bandwidths.

Ku-band high power HFET amplifiers using split-cell matching methods

This paper presents the design, fabrication, and performance of Ku-band high power HFET amplifiers using split-cell matching methods. The split-cell matching method, in which the impedance matching circuits in conjunction with FETs are split in accordance with the number of split cells, is useful for achieving high gain, high power, and high stability at high frequencies.