林 等

An MMIC variable-gain amplifier, which improves the transmission phase deviation caused by gain control, is presented. At first, it is shown that by controlling both the common-gate FET's gate bias voltage and the common-source FET's gate bias voltage, the transmission phase deviation caused by gain control of the variable-gain amplifier using a cascode-connected FET is greatly improved, In this case it is not desirable to control both of the gate bias voltages independently, because of the complexity. Thus we propose two simple gate bias voltage control circuits controlling both of the gate bias voltages-in which only one of the two ale bias voltages is controlled independently and the other is controlled dependently. Then we apply these circuits to the 1.9-GHz-band variable-gain amplifier using the cascode-connected FET, One of the control circuits is the gate bias voltage control circuit using two resistors. It is confirmed that, by applying the newly proposed circuit, phase deviation is suppressed, from between 0 degrees and -30 degrees to between +3 degrees and -5 degrees, with 25-dB gain control. The other circuit is the gate bias voltage control circuit using the FET's nonlinear characteristics. It is confirmed that, by applying the newly proposed circuit, phase deviation is suppressed, from between 0 degrees and -44 degrees to between +6 degrees and -3 degrees, with 30-dB gain control. This is a promising technique for reducing the transmission phase deviation caused by gain control of the amplifiers used in active phased array antennas.

Recently fiber oplic links have been applied to radio signal distribution networks and also to signal feeder networks for phased array antennas, because they arc able to offer wide bandwidth for achieving the high bit-rates and large capacity needed in the multimedia age. In these networks, a great many modules are needed to convert optical signals to radio signals. In order to reduce the complexity and cost of these modules, direct optical control techniques, which inject optical signals directly into microwave circuits, are very attractive. Thus, this paper proposes a novel optical control technique using tunable inductance circuits. This technique employs direct illumination as a means of optically tuning the inductance. Since the inductance value is inversely proportional to the square of the transconductance, it varies widely when the FET is directly illuminated. With direct illumination, the measured inductance variation in an experimental inductance circuit built with Pscudomorphic AlGaAs/InGaAs/GaAs HEMTs is more than 20 % from 0.5 to 2 GHz. As an application, a direct optically controlled oscillator was fabricated. The measured optical tuning range of the oscillation frequency is more than 19 % with an output power of-5±1 dBm. This is a promising technique for a variety of devices, including optically controlled oscillators, filters, phase shifters, and active antennas.

IF-band MMICs for high-speed wireless signal processing are presented. The first is a miniaturized 90 degrees divider/combiner with 2.1-dB mean transmission loss for dividing signals at 140 MHz. The second is a logarithmic/limiting amplifier which utilizes a self-phase-distortion compensation technique. More than 65-dB gain and less than 5 degrees phase deviation were obtained.

This paper proposes a low distortion technique which reduces transmitter intermodulation. It is shown that one of the third order transmitter intermodulation products generated can be reduced by using a parallel amplifier configuration which includes a 45 degrees divider and a 45 degrees combiner. It is already known that the other third order transmitter intermodulation product can be reduced by using a parallel amplifier configuration using 90 degrees hybrids. Thus, all of the third order transmitter intermodulation can he reduced by combining these configurations. This paper also shows the experimental results obtained with a parallel amplifier using 90 degrees hybrids and one using a 45 degrees divider and combiner in the K-band, The spectra of these amplifiers are compared, and it is found that third order transmitter intermodulation can be reduced by more than 29 dB in the parallel amplifier using the 45 degrees divider and combiner.

This paper demonstrates a high-Q broad-band active inductor and its application to a low-loss analog phase shifter, The proposed high-Q broad-band active inductor utilizes frequency-insensitive negative resistance to compensate constant internal losses caused by the drain-to-source conductance of the field-effect transistors (FET's), the de bias circuit, and several other factors. The measured frequency range of the fabricated InAlAs/InGaAs/InP HEMT active inductor is 6 to 20 GHz for Q values greater than 100, and 7 to 15 GHz for Q values greater than 1000, A low-loss analog phase shifter is also fabricated at C-band, This is constructed with the active inductors, the varactor diodes and the low-loss multilayer broad-side coupler in a MIC structure, Since the constant negative resistance of the active inductors also compensates the line loss of the coupler and the varactor diodes' series resistance, the measured results show a good insertion loss performance with a large phase shift, A phase shift of more than 225 degrees within a 0.8 dB insertion loss from 4.7 to 6.7 GHz, another of more than 180 degrees within 1.3 dB insertion loss from 3.7 to 8.5 GHz, and one more of more than 90 degrees within 1.4 dB insertion loss from 3.5 to 10.6 GHz were obtained.

A novel optical inductance control technique using tunable inductance circuits is presented. The technique employs direct illumination as a means of optically controlling inductance. This is a promising technique for controlling oscillators, filters, active antennas, etc.

This paper demonstrates a self phase distortion compensation technique to realize linear power amplifiers, in which the positive phase deviation from a common-source PET and the negative phase deviation from a common-gate FET cancel each other, It is confirmed both theoretically and experimentally that increasing the drain-to source conductance, G(d), causes the self phase distortion compensation effect, An experimental power amplifier for L-band personal communications systems, which employs the cascode connection, shows good phase deviation performance, More than 20-dB gain, 21-dBm output power, and 50% power added efficiency are obtained along with the adjacent channel interference of -52 dBc in 192-kHz bands at 600-kHz offset frquency from 1.9 GHz at the operating voltage of only 3 V. The demonstrated performances satisfy the specifications for the 1.9-GHz Japanese Personal Handy-phone System (PHS) utilizing the pi/4-shift QPSK modulation scheme, The proposed technique is suitable for MMIC design, and allows the design of handsets that are small, lightweight, and have long operating times.

An ultra low power consumption amplifier chip set for the 1.9 GHz Japanese Personal Handy-phone System (PHS) is presented. The chip set includes a linear power amplifier, a driver amplifier, and an LO switch amplifier. These amplifiers use Cascode FETs that provide low phase distortion, high gain, and low current operation. The power amplifier uses a new concept of a self-phase distortion compensation to achieve a record performance of 45% power added efficiency with sufficient linearity. The driver amplifier has a gain of 13.5 dB with a low power consumption of 3mW (1mA, 3V). The LO switch amplifier is a new MMIC that has both switch and buffer amplifier functions. The switch amplifier has an output power of 3 dBm, a forward gain of 15 dB, and a reverse isolation of 35 dB with a low power consumption of 6mW (2mA, 3V).

© 1995 IEEE. A novel MMIC power amplifier that uses a cascode FET with unequal gate widths is presented. The amplifier uses a new concept of self phase distortion compensation. By enlarging the gate widths of a common-source FET, output phase deviation can be improved without reducing the gain and output power. A prototype PA achieves the high power added efficiency of 50 % at the drain supply voltage of 3.5 V with sufficient linearity for the 1.9-GHz Japanese Personal Handy-phone System.