Naotaka Iwata

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A 0.1 cc high efficiency power amplifier multi chip module (MCM) employing novel enhancement-mode double-doped AlGaAs/InGaAs/AlGaAs heterojunction FETs (HJFET) has been successfully developed for 1.9 GHz wide-band CDMA handsets. The HJFET has a 5 nm thickness Al/sub 0.5/Ga/sub 0.5/As barrier layer for improving a gate forward turn-on voltage. It was also(More)
This paper presents the improvement techniques of intermodulation-distortion asymmetries with wide carrier-spacing signals in L/S-band high power amplifiers. We proposed a novel circuit technique to directly connect LC series resonant circuits to the gate and drain electrodes of the transistor die in a package for baseband terminations with a wide frequency(More)
The circuit design considerations for the traveling-wave switch (TWSW) single-pole double-throw (SPDT) monolithic microwave integrated circuit (MMIC) utilizing a fully distributed FET (FD-FET) are presented here for the first time. The normalized length of the impedance transformer for a single-pole multithrow TWSW using the FD-FET is found to be less than(More)
An L/S-band 330-W distortion-cancelled Doherty GaAs field-effect transistor (FET) amplifier has been successfully developed optimizing the main and peak amplifiers load impedance shift. The amplifier employed a pair of 28-V operation 150-W GaAs heterojunction FETs. It demonstrated low third-order intermodulation of -37 dBc with a drain efficiency of 42% at(More)
This paper describes a 28 GHz power amplifier with 4.5 W output power under CW operation. The amplifier utilizes four fully-matched MMICs, in which 0.35 /spl mu/m-long gate GaAs-based heterojunction FETs are employed. The developed power amplifier also provides the highest CW output power of 3 W over the bandwidth of 2 GHz at Ka-band.
The dependence of adjacent channel leakage power ratio (ACPR) of a heterojunction FET (HJFET) on quiescent drain current (I/sub q/) for wide-band CDMA (W-CDMA) cellular phones application is presented. Measured performance demonstrates an ACPR dip phenomenon under a low I/sub q/ condition resulting in a significant improvement on the power added efficiency(More)
This paper describes single 2.2 V operation of a two-stage MMIC power amplifier for 2.4 GHz wireless local area network applications. The MMIC with 0.76/spl times/ 0.96 mm/sup 2/ area is composed of n-AlGaAs/InGaAs/n-AlGaAs FETs with a shallow threshold voltage of -0.24 V and SrTiO/sub 3/ capacitors. The capacitors with a high relative dielectric constant(More)
A high efficiency, wide dynamic range linearized power amplifier has been developed for 1.95 GHz wide-band CDMA (W-CDMA) handsets. The amplifier is based on a developed heterojunction FET, and its linearity and efficiency are further improved by incorporating a MMIC predistorter. The output power (P/sub out/) and power added efficiency (PAE) of the(More)