Kosei Maemura

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>>

A single-chip GaAs RF transceiver for 1.9-GHz digital mobile communication systems

A 1.9-GHz single-chip GaAs RF transceiver has been successfully developed using a planar self-aligned gate FET suitable for low-cost and high-volume production. This IC includes a negative voltage generator for 3-V single voltage operation and a control logic circuit to control transmit and receive functions, together with RF front-end analog circuits-a power amplifier, an SPDT switch, two attenuators for transmit and receive modes, and a low-noise amplifier. The IC can deliver 22-dBm output power at 30% efficiency with 3-V single power supply, The new negative voltage generator operates with charge time of less than 200 ns, producing a low level of spurious outputs below -70 dBc through the power amplifier. The generator also suppresses gate-bias voltage deviations to within 0.05 V even when gate current of -144 /spl mu/A flows. The IC incorporates a new interface circuit between the logic circuit and the switch which enables it to handle power outputs over 24 dBm with only an operating voltage of 3 V. This transceiver will be expected to enable size reductions in telephones for 1.9-GHz digital mobile communication systems.

A CDMA InGaP/GaAs-HBT MMIC Power Amplifier Module Operating With a Low Reference Voltage of 2.4 V

This paper describes circuit design and measurement results of our newly developed InGaP/GaAs-HBT MMIC power amplifier (PA) module which can operate with 2.4-V low reference and low supply voltages of its on-chip bias circuits. To achieve the low-reference voltage operation, the following two new circuit design techniques are incorporated into the power amplifier: 1) AC-coupled, divided power stage configuration with two different kinds of bias feeding (voltage and current drive and only current drive) and 2) successful implementation of a diode linearizer built in the power stage. Theses two techniques allow the PA to offer smooth output transfer characteristics over a wide temperature range. Measurement results done under the conditions of 900 MHz, a 3.5-V collector voltage for power stage, and 2.4-V reference and collector voltages for the bias circuits show that the PA module meets J-/W-CDMA power and distortion requirements sufficiently over a wide temperature range from -10degC to 90degC while keeping a low quiescent current of less than 65 mA. For J-CDMA modulation, the module can deliver a 27.5-dBm output power (Pout), a 40% PAE, and a -50-dBc ACPR, while a 28-dBm Pout, a 42% PAE, and a -42-dBc ACLR are achieved for W-CDMA modulation.

A 3.3V, 1W GaAs One-Chip Power Amplifier MMIC for Cellular Phones

A 900-MHz-band 1W one-chip power amplifier MMIC, which operates at the low-supply voltage of 3.3 V and includes all bias and output matching circuits, has been developed for cellular phones. It is capable of delivering output power over 1.1 W with a power added efficiency of 43% at 3.3 V. With its extremely small chip size of 2.5 mm × 3.48 mm, it is less than one fifth the size of previously reported multi-chip ICs (MCICs). This new MMIC, the characteristics of which are compared with those of the existing MCICs, can be expected to contribute to the realization of smaller, lighter-weight cellular phones.

The 200 MHz- and 1.5 GHz-band GaAs monolithic quadrature modulator ICs

The 200-MHz and 1.5-GHz-band quadrature modulator ICs are developed. The ICs integrate a digital frequency divider, double-balanced FET mixers, and a combiner. The power consumptions of the 200-MHz- and 1.5-GHz-band modulator ICs are 100 mW and 160 mW, respectively. These ICs realize low distortion below -50 dBc, and low image and carrier rejections below -40 dBc and they reduce the phase-error to less than 1.1 degrees . The modulator ICs have excellent spectrum efficiency and are useful in realization of small-size and lightweight handy radio telephone equipment. Circuit design, fabrication process, and device performance are outlined.<<ETX>>

A 2.4-V low-reference-voltage operation, InGaP HBT-MMIC power amplifier module for CDMA applications

This paper describes circuit design and measurement results of a newly developed InGaP/GaAs HBT MMIC power amplifier module (PA) which can operate with 2.4-V low reference (Vref) and supply voltages of its on-chip bias circuits. To achieve the low-Vref operation, the following two new circuit design techniques are incorporated into the IC: (i) two different kinds of bias feeding (current feed, and voltage-/current-feed) to AC-coupled power stages, and (ii) successful implementation of a diode linearizer built in the power stage. Measurement results at 900 MHz, a 3.5-V Vcc , and a 2.4-V Vref show that the PA meets J-/W-CDMA power and distortion specifications sufficiently over a wide temperature range from -10 to 90degC while keeping a low quiescent current of less than 65 mA. For J-CDMA modulation, the PA can deliver a 27.5-dBm Pout, a 40% PAE, and a -50-dBc ACPR, while a 28-dBm Pout , a 42% PAE, and a -42-dBc ACLR are achieved for W-CDMA modulation