Kenichi Miyaguchi

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.

High-isolation series-shunt FET SPDT switch with a capacitor canceling FET parasitic inductance

A novel series-shunt FET narrow-band high-isolation single-pole double-throw switch, which employs series capacitors to cancel the parasitic inductances has been developed. The proposed switch can have significantly high isolation characteristics at higher frequency. The fabricated two switches have demonstrated high isolation characteristics of 28.9 dB in the 28- and 18-GHz band, respectively.

An Ultra Compact C-Band 5-Bit MMIC Phase Shifter Based on All-Pass Network

An ultra compact 5-bit MMIC phase shifter, operating in the C-band, is presented. The proposed phase shifting circuit utilizes the lumped-element all-pass network topology. The transition frequency of the all-pass network which determines the size of the circuit is set to be much higher than the operating bandwidth, which results in an extremely small chip size of the phase shifter in a relatively low frequency range. The MMIC phase shifter has been successfully fabricated with a die size of 1.72mm times 0.81mm (1.37mm2) and achieved a fractional bandwidth of 10%, demonstrating an insertion loss of 5.7 dB plusmn 0.8 dB and an RMS phase shift error of less than 2.3deg in the C-band. To our knowledge, the MMIC phase shifter is the smallest among the reported digital phase shifters which cover a total phase shift of 360deg for the C-band

A Millimeter-Wave Low-Loss and High-Power Switch MMIC using Multiple FET Resonators

A millimeter-wave low-loss and high-power terminated switch MMIC is developed. Our invented switch is designed based on a non-linear relationship between the parallel resistance of an FET and its gate width. Our measurements of the parallel resistance with different gate width have revealed that the resistance is inverse proportion to a square of the gate width. By using this relationship, we have found the fact that the multiple FET resonators with smaller gate width and high inductance element realize high-Q performance for the same resonant frequency. Since the power handling capability is determined by the total gate width, our switch circuit could reduce its insertion loss, keeping the high-power performance. To verify this methodology, we fabricated a switch MMIC. The MMIC had insertion loss of 2.86dB, isolation of 37dB at less than 33dBm of the input-power

Switches with capacitor cancelled parasitic inductance of FET

GaAs SPDT FET switches have been developed with capacitor cancelled parasitic inductance of FET. The switches employed series-shunt configuration. The switches have been shown to have significantly higher isolation and higher frequency operation compared to conventional switch. Isolation of 28.9 dB at 18 GHz and 30 GHz has been achieved.

An ultra broad band reflection type 180/spl deg/ phase shifter with series and parallel LC circuits

An ultra broad band reflection type 180/spl deg/ phase shifter is proposed. It is composed of a 3-dB Lange coupler and a pair of novel reflective terminating circuits. The reflective terminating circuit switches two states of series and parallel LC circuits and it can achieve a 180/spl deg/ phase difference independently of frequency. Using a simplified circuit model without parasitic circuit elements, we have derived the determining condition of circuit elements to achieve 180/spl deg/ phase difference for all frequencies. The fabricated reflective terminating circuit MMIC has achieved a phase difference of 183 +/- 3/spl deg/ over 0.5 to 30 GHz. The 180/spl deg/ phase shifter MMIC has demonstrated a phase shift of 187 +/- 7/spl deg/ over 0.5 to 20 GHz band.