Kazutomi Mori

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.

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>>

High-Current Backside-Illuminated Photodiode Array Module for Optical Analog Links

We have developed a high-current photodiode (PD) array module that consists of a beam splitter, which splits a light beam from a single-mode fiber into four beams with identical powers, a backside-illuminated InGaAs p-i-n PD array, and a two-stage Wilkinson RF power combiner. To obtain a linear PD response, the PD is equipped with a partially depleted absorber, which reduces the bias voltage. To prevent thermal failure, the backside-illuminated PD structure is used, which reduces the thermal resistivity. The beam splitter is fabricated using optical contacts at the SiO2 interfaces between a coating film and a neighboring prism to prevent degradation of the adhesive glue at the prism interfaces along the optical path; therefore, light with a power of a watt level can be used. The two-stage Wilkinson combiner combines four RF outputs of the PD array into a single-RF output through a K connector; the combiner also works as an impedance-matching circuit. Experimental results reveal that an RF power output of 29.0 dBm can be obtained at a frequency of 5 GHz, and good intermodulation distortion characteristics with a third-order intercept point of 32.5 dBm can be achieved.

C-band GaN HEMT Power Amplifier with 220W Output Power

In this paper, GaN HEMT high power amplifiers operating at C-band are presented. Improvement of device performance and reduction of thermal resistance with larger gate pitch enabled 1.4 times power density compared with the previous work [1]-[2]. 167 W output power was extracted from a single chip GaN HEMT with 7 W/mm power density. 2-chip amplifier have recorded 220 W output power at C-band, which is the highest output power ever reported for GaN HEMT amplifiers at C-band and higher bands.

A 20 mA quiescent current CV/CC parallel operation HBT power amplifier for W-CDMA terminals

A novel constant voltage/constant current (CV/CC) parallel operation HBT power amplifier (PA) configuration is proposed. By combining two HBTs having different base bias circuits for each (one is CV and the other is CC), non-linearity at large back-off region can be canceled out. Therefore, both low quiescent current and enough ACPR performance can be achieved. The fabricated CV/CC parallel operation HBT PA demonstrates extremely low quiescent current of 20 mA and ACPR of less than -38 dBc at the output power range up to 27.5 dBm.

GaN HEMT 60W Output Power Amplifier with Over 50% Efficiency at C-Band 15% Relative Bandwidth Using Combined Short and Open Circuited Stubs

In this paper, a broadband high efficiency amplifier is proposed, which uses both short and open circuited stubs for simultaneous broadband impedance matching for fundamental frequency and 2nd-harmonic. The developed GaN HEMT amplifier with 16 mm gate periphery has achieved over 60 W output power with over 50% drain efficiency (over 45% power-added-efficiency) across 15% relative bandwidth at C-Band. This is the state-of-the-art efficiency of GaN HEMT high power amplifier with over 50 W output power at C-band to the best of our knowledge.

5.8GHz ETC SiGe-MMIC Transceiver having Improved PA-VCO Isolation with Thin Silicon Substrate

A fully integrated SiGe-MMIC transceiver having a power amplifier (PA), a transmit/receive switch (T/R SW), and a voltage controlled oscillator (VCO) is developed for electric toll collection system (ETC) terminals. To improve the isolation between the PA and the VCO, the back-polish technique of the silicon substrate (127mum thickness) is employed. Electro-magnetic simulation shows that a MMIC of 127mum thickness achieves the isolation improvement of 12.3dB compared with that of conventional 300mum thickness. As a result, the USB/LSB unbalance of the transmitted amplitude shift keying (ASK) signal can be reduced from 4.2dB to 1.2dB at 13dBm output power. The MMIC transceiver fabricated in 0.35mum SiGe BiCMOS process achieves the maximum output power of 15.5dBm with the adjacent channel power ratio (ACPR) of -33.5dBc

An L-band high efficiency and low distortion power amplifier module using an HPF/LPF combined interstage matching circuit

A three stage high power amplifier (HPA) module for wide-band CDMA handy phones using an HPF/LPF combined interstage matching circuit has been developed. An HPF/LPF combined interstage matching circuit can realize both the optimum load impedance of the second stage FET and the optimum source impedance of the third stage FET to achieve high efficiency. The developed three stage HPA module, size of which is 0.08cc (7 mm/spl times/7 mm./spl times/1.7 mm), achieves a power-added efficiency of 43.9% and an output power of 27.1 dBm with an adjacent channel leakage power (ACP) of -38 dBc at 1.95 GHz.

Over 65% efficiency 300 MHz bandwidth C-band internally-matched GaAs FET designed with a large-signal FET model

Over 65% efficiency 300MHz bandwidth C-band internally-matched GaAs FET has been developed by using a large-signal FET model. In order to achieve high efficiency in broad-band, optimum impedances at each frequency are estimated by using the large-signal FET model. The large-signal FET model is based on Angelov model. The capacitance equations of the model are improved to satisfy charge conservation. The model parameters are extracted for a unit cell FET with a small gate width. The unit cell FET model was scaled up to one chip FET model with a wide gate width, considering increase of source inductance by sharing via holes. The developed C-band internally-matched FET has achieved power-added efficiency (PAE) of over 65% across 300MHz bandwidth.

An X-Band 50W-Output/30%-PAE GaN Power Amplifier with Bandwidth/Ripple-Optimized Bandpass Impedance-Matching Networks

An X-band 50 W GaN power amplifier (PA) is presented, mainly focusing on its impedance-matching networks to realize a specified operating bandwidth of 18 %. Bandpass impedance-matching networks (IMNs) with Chebyshev response are adopted in the PA, where a FET and a pre-matching transmission line can be approximately seen as a shunt parallel-resonant circuit. Mismatch-loss ripple of the Chebyshev IMN can be theoretically optimized in terms of Q-factor of the FET and a specified operational bandwidth. The designed PA has achieved an output power of 50 W and a power-added efficiency (PAE) of more than 30 % in the 18 % relative bandwidth.