Hideki Takasu

W-band SPST transistor switches

A single-pole, single-throw (SPST) transistor switch has been developed, Three types of switches, that is, GaAs MESFET, AlGaAs-GaAs HEMT, and pseudomorphic HEMT (PM-HEMT), have been fabricated, and the performances at W-band are compared. To reduce on-state resistance and off-state capacitance, gate length was varied as a parameter. Moreover, an inductance for resonance was installed in parallel to the off-state capacitance between source and drain to obtain a high isolation, A relatively low insertion loss of 1.6 dB and a high isolation over 20 dB at W-band have been obtained from the 0.8-μm gate length PM-HEMT.

Ka-band low loss and high power handling GaAs PIN diode MMIC phase shifter for reflected-type phased array systems

This paper describes the design and performances of a GaAs PIN diode and a reflected-type MMIC phase shifter in Ka-band. With optimized geometries and fabrication process, the GaAs PIN diode has shown the highest fmax so far. Excellent performances of MMIC phase shifters have also been obtained.

S-band MMIC digital attenuator with small phase variation

This paper describes MMIC digital attenuator with small phase variation in S-band. The five-bit digital attenuator employing SPDT switched circuits has obtained excellent performance. It has been shown that a minimum attenuation of 7.05 dB, r.m.s. amplitude error of 0.09 dB, and r.m.s. phase variation of 1.38 degrees were obtained.

New design of X-band GaAs MMIC phase shifter using improved equivalent circuit model

An improved yet simple equivalent circuit of a GaAs FET switch is proposed that takes parasitic distributed-line effects of the FET into account. X-band five-bit GaAs MMIC phase shifters designed using the model show a good agreement between the design and the measurement.<<ETX>>

K-band GaAs MMIC phase shifter using self-switched filter circuits

This paper describes a performance of a K-band GaAs MMIC four-bit phase shifter using self-switched filter circuits which take account into the distributed effects of GaAs FET used as the switching device.

Ka-band single-pole double-throw MMIC switch using low-loss GaAs PIN diode

To realize low-insertion-loss and high-power-handling GaAs PIN diode monolithic microwave integrated circuit (MMIC) switches in the millimeter-wave region, a new switching device having characteristics of higher switching cutoff frequency and higher breakdown voltage is required in the place of conventional switching devices such as metal semiconductor field effect transistor (MESFET) and pseudomorphic HEMT. In this paper, equivalent circuits of the developed GaAs PIN diode and their detailed performance are first presented, and the requirements for realizing the GaAs PIN diode having the characteristics of lower insertion loss and high breakdown voltage in the millimeter-wave region are described. The design and performance of a millimeter-wave MMIC switch using the GaAs PIN diode are then described.