Yasuo Mitsui

A microwave miniaturized linearizer using a parallel diode with a bias feed resistance

A miniaturized linearizer using a parallel diode has been developed. It is composed of a parallel diode and a resistance for d.c. bias feed. The linearizer utilizes a nonlinear resistive element of the diode. In this paper, the operation principle of the linearizer is described. The parallel diode provides a high temperature stability and readiness of bias voltage adjustment. BY applying this linearizer to an S-band power amplifier, an improvement of ACP of 5 dB and power added efficiency of 8.5% has been achieved for the /spl pi//4-shift QPSK modulated signal.

Analysis of class-F and inverse class-F amplifiers

Class-F: the 2nd harmonic is short and the 3rd harmonic is open, inverse class-F: the 3rd one is short and the 2nd one is open, and intermediate harmonic tunings are analyzed by simulations. The best tuning that exhibits the highest efficiency has been found to move from class-F to inverse class-F in accordance with larger gain-compression, higher load resistance and smaller Ron. The Ron dependence of the efficiency is also described by using a waveform theory.

A 1.9-GHz-band GaAs direct-quadrature modulator IC with a phase shifter

A 1.9-GHz-band direct-quadrature modulator IC has been developed for digital cordless telephone use. In the 1.9-GHz high-frequency band, both carrier and image rejections as low as -40 dBc have been obtained with low-power dissipation of 110 mW, corresponding to phase error below 1.1 degrees . A newly developed circuit configuration, which combines a quadrature phase shifter with drivers, make this excellent spectrum efficiency and low-power dissipation possible. This modulator IC is expected to contribute to the realization of enhanced digital mobile communication systems such as digital and cordless digital cellular telephones.<<ETX>>

Ka-Band ultra low noise MMIC amplifier using pseudomorphic HEMTs

A Ka-band monolithic low noise two stage amplifier has been developed using an AlGaAs/InGaAs/GaAs pseudomorphic HEMT with a gate length of 0.15 /spl mu/m. For a superior noise figure, the MMIC was optimized by inserting a low loss resonator type stabilizing circuit without sacrificing the gain performance. The amplifier has achieved a 1.0 dB noise figure with an associated gain of 18.0 dB at 32 GHz. These results are the best of AlGaAs/InGaAs/GaAs P-HEMT MMICs ever reported to date.

Small-chirp 40-Gbps electroabsorption modulator with novel tensile-strained asymmetric quantum-well absorption layer

A small-chirp 40-Gbps electroabsorption modulator (EAM) with a novel tensile-strained asymmetric quantum-well (QW) absorption layer has been demonstrated for the first time. The strain and the band line-up of the asymmetric QW structure were designed in order to obtain a small-chirp operation, a clear eye opening, and a high extinction ratio simultaneously. The chirp measured as /spl alpha/-parameter was reduced without any penalty of extinction ratio and eye opening. The measured /spl alpha/-parameter was smaller than 1.5 at any bias voltage from 0 to -2 V. The measured 3-dB bandwidth of a 75-/spl mu/m-long EAM exceeded 50 GHz at -1 V bias voltage. Under a 40-Gbps modulation, a clear eye opening was obtained, and the eye diagram showed no violation of the standard STM256/OC768 mask. The measured dynamic extinction ratio was over 11 dB.

A Ka-Band GaAs Power MMIC

A Ka-band GaAs power MMIC with source island via-hole PHS structure and monolithic power divider /combiner circuits was developed and reliability study was performed. This source island via-hole technique successfully reduced both thermal resistance and source parasitic inductance of the MMIC. The 3200 µm MMIC gave power output at 1dB gain compression of 1.1 W, linear power gain of 4.0 dB and power added efficiency of 10.8 % at 28 GHz. No failure was observed in the temperature cycling, the DC running and the high temperature storage tests.

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.

A microwave miniaturized linearizer using a parallel diode

A miniaturized linearizer using a parallel diode has been developed. It is composed of a parallel diode and a resistance for d.c. bias feed. The linearizer utilizes a nonlinear resistive element of the diode. In this paper, the operation principle of the linearizer is described. The parallel diode provides a high temperature stability and readiness of bias voltage adjustment. BY applying this linearizer to an S-band power amplifier, an improvement of ACP of 5 dB and power added efficiency of 8.5% has been achieved for the /spl pi//4-shift QPSK modulated signal.

Fluorine limited reliability of AlInAs/InGaAs high electron mobility transistors with molybdenum gates

A highly reliable AlInAs/InGaAs high electron mobility transistor with the projected lifetime of 10/sup 6/ hours at 125/spl deg/C is developed. The gate electrode sinking is eliminated by adopting molybdenum gate contact metal, and the carrier passivation is controlled by eliminating the extrinsic fluorine containing processes. The experimental results and theoretical calculation indicate the present reliability is limited by the intrinsic fluorine contamination from the air.

dBm average optical output power operation of small-chirp 40-gbps electroabsorption Modulator with tensile-strained asymmetric quantum-well absorption Layer

A small-chirp 40-Gbps electroabsorption modulator (EAM) with high optical output power capability has been developed for the first time. An optimized tensile-strained asymmetric quantum-well structure is employed as the absorption layer of the EAM so that small chirp and reduction of the lifetime of the photogenerated holes for high optical output power tolerance is obtained. Deteriorations of frequency response and chirp due to carrier pileup under high optical output power conditions were prevented by enhancing carrier sweepout, which was experimentally confirmed as a hole lifetime as short as 35 ps under high optical output power conditions. As a result, good frequency response (bandwidth > 30 GHz) and small chirp (/spl alpha/<1) were obtained under the condition of the zero bias voltage and +4.5 dBm continuous-wave (CW) optical output power (P/sub out,CW/). Clear eye opening and high dynamic extinction ratio under 40-Gbps non-return-to-zero modulation persisted to a high average output power (P/sub out,ave/) condition of P/sub out,ave/=+1.0 dBm.