Hitoshi Kurusu

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.

V-band high-power low phase-noise monolithic oscillators and investigation of low phase-noise performance high drain bias

This paper reports on the excellent performance of V-band monolithic high electron-mobility transistor (HEMT) oscillators, and discusses oscillation characteristics on drain bias. With regard to output characteristics, double-hetero (DH) HEMT (especially with a high-density Si-planar doped layer) are superior to single-hetero (SH) HEMTs. A monolithic microwave integrated circuit (MMIC) oscillator has been developed with a planar doped DH HEMT and has achieved the peak output power of 11.1 dBm at a 55.9-GHz oscillation frequency. Phase noise of -85 dBc/Hz at 100-kHz offset and -103 dBc/Hz at 1-MHz offset have been achieved at a drain voltage of 5.5 V and a gate voltage of 0 V. These characteristics have been achieved without any buffer amplifiers of dielectric resonators. This study has revealed that the phase noise decreases as drain voltage increases. This phenomenon is caused by lower pushing figure and lower noise level at a low-frequency range obtained under a high drain voltage. It is because the depletion layer in the channel is extended to the drain electrode with increase of drain voltage, resulting in the small fluctuation of the gate-to-source capacitance. We also investigate low-frequency noise spectra of AlGaAs-InGaAs-GaAs DH HEMTs with different bias conditions. The low-frequency noise decreases for more than 3 V of the drain voltage. A unique mechanism is proposed to explain this phase noise reduction at high drain voltage.

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.

1 watt compact Ka-band MMIC power amplifiers using lumped element matching circuits

A compact MMIC chip set for Ka-band communication systems has been developed. A two stage power MMIC amplifier using only lumped elements and narrowly spaced lines for the matching circuit delivers 1.44 watt at 30 GHz with a very small die size of 1.94 mm/spl times/2.0 mm. The designing scheme is confirmed to be useful for cost reduction.

20-30 GHz broadband MMIC power amplifiers with compact flat gain PHEMT cells

20-30 GHz band MMICs have been successfully developed using two types of novel compact size flat gain PHEMT cells that have flat maximum available gain and sufficient stabilities over a wide frequency range of 20-30 GHz. One type is a feedback type. The other has an equalizer circuit at the gate of a PHEMT. The MMIC delivers gains of over 18 dB and P1dB of over 22 dBm. These results show this method is very effective in designing broadband MMICs.

A Ku-Band Matched Embedded-FET Phase Shifter

A Ku-band matched embedded-FET phase shifter achieving compact and low insertion loss performance is described. It consists of only a few circuit elements of a series embedded-FET incorporated with a high impedance line and an inductive matching network switched by an SPST switch. A six-bit phase shifter has been developed, consisting of these matched embedded-FET phase shifters for lower bit sections (22.5 °, 11.25 °, 5.625°) and high pass / low pass type phase shifters [1]-[2] for higher bit sections. It has a small size and a low insertion loss.

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.

A Ka-Band High Power Monolithic HEMT VCO Using a Sub-resonatore Circuit with Phase Control Architecture

This paper reports on a high output performance of a Ka-band monolithic HEMT Voltage Controlled Oscillator(VCO). This VCO has a sub-resonator in order to avoid reduction in Q-factor of a resonator. Circuit elements of the sub-resonator are optimized to achieve a wide tuning range as well as high output power and low phase noise performances. In addition, an AlGaAs/InGaAs double-hetero structure High Electron Mobility Transistor(HEMT) is employed in the VCO to obtain a high output performance. A high output power of 19.4 dBm has been achieved at an oscillation frequency of 36.2 GHz. This performance has been achieved without any buffer amplifiers. A tuning range of more than 2.5 GHz is also obtained with a stable high output power. To our knowledge, this represents the highest output power of monolithic VCO without any buffer amplifiers.