Kazuhisa Yamauchi

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.

A novel series diode linearizer for mobile radio power amplifiers

A novel series diode linearizer has been developed for mobile radio power amplifiers. It is composed of a series diode with a parallel capacitor, which provides positive amplitude and negative phase deviations with the increase of input power, and can compensate AM-AM and AM-PM distortions of power amplifiers. Applying this linearizer to 1.9 GHz MMIC power amplifier for the Japanese Personal Handy-phone System (PHS), an improvement of adjacent channel leakage power (ACP) up to 5 dB has been achieved for the /spl pi//4-shifted QPSK modulated signal.

Negative Group Delay Circuit for Feed-Forward Amplifier

We present a design and an implementation of a negative group delay circuit, which consists of lumped parameter element. It is very small and simple circuit. The circuit is composed of three resonators with resisters, which are arranged to pi type circuit to improve the reflection. We discuss the principle of a negative group delay circuit and apply the circuit to the feed-forward amplifier. It is confirmed that the delay line of the distortion cancellation loop is shortened 40% by connecting the circuit to the driver stage of the error amplifier. The efficiency of the feed-forward amplifier has been improved from 9% to 12%.

A novel amplitude and phase linearizing technique for microwave power amplifiers

A novel amplitude and phase linearizing technique for microwave power amplifiers has been developed. It employs a series feedback amplifier with a large source inductance as a predistortion linearizer, which provides positive amplitude and negative phase deviations for input power and can compensate for AM-AM and AM-PM distortions of power amplifiers. Applying this technique to a 1.9 GHz MMIC power amplifier for use in the Japanese Personal Handy-Phone System (PHS), an improvement of adjacent channel leakage power (ACP) up to 7 dB has been achieved when it is used for /spl pi//4-shift QPSK signal.<<ETX>>

A 68% efficiency, C-band 100W GaN power amplifier for space applications

This paper describes a high efficiency (68%), high output power (100W), high reliability GaN HEMT amplifier for C-band space applications. The high efficiency is achieved by 2nd-harmonic frequency (2fo) tuning circuits in the input and output matching circuits. The input circuit uses open-ended stubs located nearby FET gate terminals for setting the 2fo reflection-phase at the optimum phase. In the output circuit, the optimum 2fo reflection phase is realized using three transmission-line transformers while matching loss is kept low at fundamental frequency. In addition, a 3000 hours RF overdrive life test reveals that an estimated mean time to failure (MTTF) is 1×107 hours at 150°C channel temperature, proving that the amplifier has sufficient reliability for space applications. To the best of our knowledge, the efficiency of 68% is the highest of 100-W class C-band amplifiers ever reported, and is also comparable to that of commercially available traveling wave tube amplifiers.

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.

An 18 GHz-band MMIC linearizer using a parallel diode with a bias feed resistance and a parallel capacitor

An 18 GHz-band MMIC linearizer using a parallel diode with a bias feed resistance and a parallel capacitor has been proposed. This linearizer has weak positive gain deviation and its gain deviation can be controlled without changing phase deviation. By applying this linearizer to an 18 GHz-band power amplifier, an improvement of IMD3 of 20 dB has been achieved.

X-band MMIC power amplifier with an on-chip temperature-compensation circuit

An X-band MMIC power amplifier with an on-chip temperature compensation circuit has been presented. The temperature compensation circuit is composed of a diode and a resistor. The compensation circuit is applied to a 4 stage X-band MMIC power amplifier. The gain variation is improved from 5.5 dB to 1.3 dB in the temperature range between -10 degC and +80 degC.

MMIC development for millimeter-wave space application

The latest millimeter-wave monolithic-microwave integrated-circuit (MMIC) developments and technologies at the Mitsubishi Electric Corporation, Kanagawa, Japan, concerning high power amplifiers, low-noise amplifiers and phase shifters have been summarized. It has been shown that high-efficiency, low-noise, and low-loss performance for millimeter-wave space applications can be achieved by employing pseudomorphic high electron-mobility transistor (p-HEMT) MMIC technology. The investigation for gamma-ray irradiation hardness has cleared that millimeter wave p-HEMT MMICs have over a 100 years of life against gamma-ray irradiation in the space environment.

A 45% power added efficiency, Ku-band 60W GaN power amplifier

A Ku-band 60W GaN power amplifier is presented. To obtain the high efficiency, new matching circuit topology to control the reflection phase at the 2nd harmonic frequency (2fo) is applied to the power amplifier. The measured power added efficiency (PAE) of 44.9% with the output power of 47.9dBm (62.2W) is obtained in the 15GHz-band. To the best of our knowledge, the PAE is the highest of the Ku-band GaN power amplifiers reported to date.