James E. Degenford

Harmonic Mixing with an Anti-Parallel Diode Pair

An analytical and experimental investigation of the properties of an antiparallel diode pair is presented. Such a configuration has the following unique and advantageous characteristics as a harmonic mixer: 1) reduced conversion loss by suppressing fundamental mixing products; 2) lower noise figure through suppression of local oscillator noise sidebands; 3) suppression of direct video detection; 4) inherent self protection against large peak inverse voltage burnout. These results are obtained without the use of either filters or balanced circuits employing hybrid junctions.

Stability and improved circuit modeling considerations for high power MMIC amplifiers

The cluster-matching approach for large-periphery power FETs brings with it certain problems including more complex circuitry and additional modes of possible oscillations. Solutions to these problems are offered including an analysis of the modes along with methods of suppression and improved circuit modeling. These solutions were implemented in the design of a two-stage, 1.6-W monolithic power amplifier which is also discussed.<<ETX>>

94 GHz subharmonically pumped MMIC mixer

A 94-GHz subharmonically pumped antiparallel diode pair MMIC (monolithic microwave integrated circuit) mixer with a short-circuit sum frequency termination is described. Advantages of the mixer configuration include (1) reduced conversion loss, (2) elimination of the need for an area-consuming hybrid junction while retaining the separation of local oscillator (LO), RF, and intermediate frequency ports, (3) inherent LO noise sideband suppression, and (4) very small size and cost.<<ETX>>

Class B Operation of Microwave FETs for Array Module Applications

In addition to the well known class B advantages of high eta /sub PA/ and self turn on for pulsed operation, it is shown herein that class B FET amplifiers have several other important features including: 1) Significantly reduced power dissipation 2) A dynamic range of typically 8-10 dB over which gain is constant and power added efficiency is >30%. 3) Phase behavior (static and dynamic) is comparable to that observed with similar FETs operated class A. 4) Absence of erratic phase behavior during pulse turn-on and turn-off. These features make class B operation of power FETs very attractive for phased array module applications.

A GaAs MMIC PIN diode receiver protector with switchable attenuator

Design and performance of a unique X-band GaAs MMIC PIN diode receiver protector (RP) with switchable attenuator is described with a maximum average and peak leakage levels of 17 dBm and 20 dBm respectively. The fast acting 8 diode RP requires no external biasing and exhibits a recovery time of 50 ns. The MMIC includes a switchable 13 dB attenuator after the RP. Two RP/attenuator circuits for balanced operation are included in a 120 by 150 by 6 mil MMIC which exhibits only 0.55 to 0.7 dB loss, and a return loss of 15 to 30 dB over an octave bandwidth.

High Efficiency One, Two, and Four Watt Class B FET Power Amplifiers

A family of X-band amplifier utilizing the higher efficiency of class B operation has been designed and fabricated. This paper describes the circuitry and performance of 1 watt single-ended, 2 watt push-pull, and 4 watt dual push-pull amplifiers having typical power-added efficiencies of 45%, 40%, and 35%, respectively, in a 1 GHz bandwidth, with associated gains of 5.8 dB, 5.4 dB, and 5.0 dB . Additional data is given for fifteen each of the 1 watt and 2 watt units to show the consistency of their performance.

Processing tolerance and trim considerations in monolithic FET amplifiers

This paper will report on the application of direct ion implantation into unbuffered GaAs substrates for FETs and monolithic power amplifiers. The effects of processing tolerances and compensating trim adjustments on the performance of a 2-stage 1W octave bandwidth amplifier will be analyzed.

Octave Bandwidth High Speed Limiter with Uniform Suppression Characteristics

The performance of several octave-bandwidth diode clipper/limiters having uniform suppression characteristics over the 2.0 to 4.0 GHz octave is discussed. Suppression over the band is 4.0 dB or greater for a structure using Silicon diodes and 3.5 dB or greater for a similar structure using GaAs diodes.