Hikaru Ikeda

High-efficiency low adjacent channel leakage GaAs power MMIC for 1.9 GHz digital cordless phones

We report on the fabrication of highly efficient GaAs MESFETs, the design for low distortion, and the performance of this MMIC. Two power MESFETs and input, interstage, and output matching circuits were integrated in a very small chip size of 1.0 mm/spl times/1.5 mm. This MMIC achieved an output power of 22 dBm at 1.9 GHz with high power added efficiency of 49.5% and low adjacent channel leakage power of -56 dBc under the low operating voltage of 3.0 V. This result represents one of the highest efficiencies that have been reported. This MMIC has a promising future for 1.9 GHz digital cordless phone applications. >

Phase distortion mechanism of a GaAs FET power amplifier for digital cellular application

A conventional class AB amplifier with high efficiency has phase distortion which is not suitable for a pi /4-shift quadrature phase shift keying (QPSK) signal. A new nonlinear GaAs FET model, instead of the conventional large signal GaAs FET model, is presented. It incorporates the phase distortion mechanism in a class AB amplifier. Using the results of the analysis, the authors designed a low phase distortion power amplifier by optimizing circuit parameters and device parameters, which had a low phase variation of less than 2 degrees .<<ETX>>

A high efficiency and low distortion GaAs power MMIC design in the wide load impedance range by extended use of load-pull method

A new design technique by an extended use of the load-pull method for a high efficiency and low distortion power amplifier in wide range of load impedances is proposed. A two stage GaAs MMIC power amplifier which meets the Japanese PHS standard with high efficiency and low distortion within load VSWR of 3 was designed by using this method.

Analogue/Digital dual power module using ion-implanted GaAs MESFETs

An analogue and digital dual power module using ion-implanted GaAs MESFETs with high breakdown voltage has been developed for North American Digital Cellular (NADC). In the analogue operation, the module exhibited high power-added efficiency (PAE) of 56.0% at Vdd=3.7 V. In the digital operation, the high efficiency of 46.9% and the low adjacent channel leakage power (Padj) of -29.1 dBc at +30 kHz Padj and of -52.7 dBc at +60 kHz Padj were simultaneously obtained at f=836.5 MHz, Pout=31.0 dBm and Vdd=4.7 V. This device is quite suitable for the dual mode application.<<ETX>>

A low distortion and high efficiency parallel-operation power amplifier combined in different phases in wide range of load impedances

We proposed a new four-paralleled power amplifier combined in different phases in order to accomplish a low distortion and high efficiency in a wide range of load impedances. We studied them by simulation and experiment and realized an amplifier in which adjacent channel leakage power of /spl pi//4-DQPSK modulation was improved by 13 dB in the range of load VSWR/spl les/3 without decreasing efficiency.

A computer aided accurate adjustment of cellular radio RF filters

An accurate and speedy tuning algorithm for cellular radio filters based on performance simulation of circuit network and optimization process is presented. From the measured performance of an untuned sample, the amount of adjustment to be tuned is calculated. The experimental results for a five-resonator filter show the great advantage of this method, which reduces the tuning time from several hours to 5 min. A reference table of the relation between a trimming amount and a frequency change prepared in the program would reduce the computation time even more.<<ETX>>

1.2kW power combiner unit using phase control for 2.4GHz band

The microwave power source is widely used for heating and dryness, etc. so far. To solve problem (high voltage and short life time, difficult control) of the magnetron used now, semiconductor (GaN-HEMT, LDMOS) is examined. It is necessary to combine several modules to get 1kW, because the output power of semiconductor devices is about 200W. When output power and phase of each module are different, we analyzed the combined output power. We achieved 1.2kW output power by controlling the output of each module.

First pass design of a high power 145W, high efficiency class-J GaN power amplifier using waveform engineering

This paper presents a high power, high efficiency RF power amplifier using GaN on Si heterojunction field effect transistor (HFET) designed using waveform engineering. To investigate the high efficiency operation of the GaN HFET, waveform engineering, employing harmonic active load-pull measurements is conducted, yielding 79W output power and 73.9% drain efficiency under class-J operation. The realized PA based on a larger periphery is designed using a scaled optimum output impedance obtained during the HFET investigation, and exhibits 145W output power and 73.8% drain efficiency with drain bias of 40V under 1/10 pulse measurement conditions. The presented PA is promising for application in RF base station systems.

2.4GHz-band high power and high efficiency solid-state injection-locked oscillator using imbalanced coupling resonator in feedback circuit

A 2.4GHz-band high power and high efficiency injection-locked oscillator has been developed for use in the microwave ovens having uniform heating as well as subtle temperature control. With the use of the imbalanced coupling resonator in the feedback circuit, an output power of 210W and an efficiency of 51% have been successfully obtained at 2.45GHz, where a reference signal of less than 1/10,000 has been injected. The high power and high efficiency solid-state injection-locked oscillators presented in this paper has an advantage in long life, frequency and phase controllability, and low voltage operation, which can be useful for realizing an accurate temperature control in chemical reactions as well as the spot and uniform heating of microwave ovens.