Kenneth P. Weller

DC boosting effect of active bias circuits and its optimization for class-AB InGaP-GaAs HBT power amplifiers

In this paper, dc sourcing capability (DSC), which is a very important consideration in design of active bias circuits for power amplifiers based on bipolar technologies, will be explained. The nonlinear effect of bias circuits on the dc sourcing characteristics has been analyzed with simplified circuits for power amplifiers using the Volterra series. The analysis shows that the second-order distortion generated by a bias buffer transistor can boost bias level of the RF transistor to compensate finite DSC available in the absence of this effect. The bias-level boosting due to RF injection can be optimized by tuning the value of a series resistor between the emitter of the buffer transistor and the base of the RF transistor. Amplifiers with different series resistors have been implemented and tested with an IS95-B code-division multiple-access signal at the cellular band (824-849 MHz). The experimental results verify that a circuit-level optimization for the second-order distortion of the bias circuits is very important for optimizing the linearity and efficiency of the HBT amplifiers.

Circuit Characterization of V-Band IMPATT Oscillators and Amplifiers

A circuit model has been developed to describe a class of commonly used waveguide cavities for V-band IMPATT oscillators and amplifiers. Calculated results based on this model used in conjunction with theoretical small-signal IMPATT characteristics have shown good qualitative agreement with experimental data. Detailed characterization of a small-signal V-band IMPATT amplifier and a mechanical tuned oscillator are presented, and the predicted performance is compared with measurements.

Millimeter IMPATT Sources for the 130-170-GHz Range

Device and circuit design of silicon IMPATT sources in the 130-170-GHz range is discussed. A 170-GHz source has been developed with 16 mW at the isolator output having an AM double-side-band noise-to-signal ratio of -115 dB per 1 kHz beyond 70 kHz from carrier.

Y-Band (170-260 GHz) Tunable CW IMPATT Diode Oscillators

This paper describes circuit, packaging, and device techniques used in the development of tunable CW IMPATT diode oscillators in the 170-260 GHz range. A quartz standoff package with optimum values for parasitics has been developed. A tuning range of nearly 30 GHz has been achieved with an IMPATT diode in such a package.

Low Cost X-Band MIC BARITT Doppler Sensor

An MIC X-band BARITT self-mixing oscillator has been developed. A minimum detectable signal below carrier of - 139 dB/Hz at 100 kHz away from carrier was achieved at 1-mW signal carrier. A low cost, compact and sensitive hybrid MIC Doppler sensor module was constructed, incorporating the BARITT MIC circuit and a microstrip antenna.

Millimeter-wave pulsed IMPATT diode oscillators

Double-drift silicon IMPATT diodes were fabricated for pulse source application at 35, 94, and 140 GHz. The diodes were operated with 300 ns pulsewidth and a 1.5 percent duty cycle. All sources exhibited a change in output frequency of >1 percent throughout the duration of the pulsewidth with <1 dB peak power variation. Peak pulse output power levels of 10, 2, and 0.7 W were achieved in each of the three frequency bands, respectively.

High Power V-Band Double Drift IMPATT Amplifier

A 490 mW circulator-coupled IMPATT reflection amplifier with 6.9 dB gain at 59.25 GHz and 1.9 GHz bandwidth for 1 dB rolloff has been developed using double-drift IMPATT diodes on diamond in a novel circuit designed to minimize subharmonic instabilities.

Mobile Broadband System Evolution and RF Technology Requirements for User Equipment

A review of the evolution of the air interface standards supporting personal mobile services, from voice communications to broadband video and high rate data transmission, leads to a discussion of the impact on technology requirements for the RF components needed for the generation of radio transmission from user equipment.