Robert A. Pucel

Signal and Noise Properties of Gallium Arsenide Microwave Field-Effect Transistors

Publisher Summary This chapter examines the signal and noise properties of gallium arsenide (GaAs) microwave field-effect transistors (FET). High frequency gallium arsenide field-effect transistors (GaAs FETs) have demonstrated remarkably low noise figures and high power gains at microwave frequencies. A practical microwave GaAs FET is usually fabricated by deposition or diffusion of source, gate, and drain contacts on the surface of an appropriately doped thin epitaxial n-type layer. This layer, in turn, is grown on a semi-insulating wafer by either a vapor or liquid epitaxial technique. The apparent minor role played by the negative resistance region in practical short-gate FETs suggests that radiofrequency instabilities due to this region, if they exist, occur at frequencies far above the normal frequency regime of microwave FETs. The small-signal equivalent circuit of the FET, valid up to moderately high frequencies is elaborated. It is found that noise in a microwave GaAs FET is produced both by sources intrinsic to the device and by thermal sources associated with the parasitic resistances.

A general noise de-embedding procedure for packaged two-port linear active devices

A method based on the noise correlation technique and its applications is described. The package, which need not be reciprocal, may consist of an arbitrary interconnection of linear passive elements at thermal equilibrium. Only the terminal admittance properties of the package need be known. However, in certain special cases which lead to singular submatrices of the admittance matrix, the method is inapplicable. This situation can occur when elements such as isolators are part of the package. The necessary theoretical foundation and experimental techniques to enable workers not familiar with the field to assemble the software and laboratory setup for two-port noise de-embedding is provided. The automated noise measurement system used for data acquisition and the mathematical basis for it are described in some detail. The validity of the de-embedding approach is established with extensive experimental data obtained on three MESFETs and a pseudomorphic HEMT. >

Performance of GaAs MESFET Mixers at X Band

A theoretical analysis and experimental verification of the signal properties of the GaAs MESFET mixer are presented. Experimental techniques for evaluating some of the mixer parameters are described. Experiments performed on GaAs MESFET mixers at X band show that good noise performance and large dynamic range can be achieved with conversion gain. A conversion gain over 6 dB is measured at 7.8 GHz. Noise figures as low as 7.4 dB and output third-order intermodulation intercepts of +18 dBm have heen obtained at 8 GHz with a balanced MESFET mixer.

Microwave and millimeter-wave integrated circuits

This historical review is divided into three sections: microwave integrated circuits (MICs), monolithic microwave integrated circuits (MMICs), and MIC and millimeter-wave integrated-circuit applications.

Monolithic Dual-Gate GaAs FET Digital Phase Shifter

The design, fabrication, and characterization of a fully monolithic FET digital phase-shifter circuit is described. The circuit is designed around a unique dual-gate FET structure operating as a switchable single-pole, double-throw amplifier. Each 2.5 X 3.0-mm chip has one bit (e.g., 22.5°, 90°, etc.) of phase control. The circuit, which includes all dc bypass circuitry on-chip, features thin-film lumped element capacitors and inductors, air-bridge crossovers and interconnects, via-hole frontside grounding, and integral beam leads. The fabrication of these elements is described in some detail. The phase-shifter circuit gives a peak gain of 3 dB across a 10-percent bandwidth in X-band. A method of achieving continuous phase and amplitude control using a 90° bit chip is described. Finally, phase performance of a four-bit digital phase shifter realized by cascading four monolithic active phase-shifter chips is reported.

Theory of the Esaki diode frequency converter

Abstract The small-signal conversion properties of an Esaki (tunnel) diode are represented by a simple two-port conductance matrix whose elements are certain coefficients of the periodic time-dependent diode conductance produced by the local oscillator (pump). Because of the negative slope in the diode I–V characteristic, arbitrarily high conversion gain is possible when certain conditions are satisfied by these coefficients. In terms of these coefficients and other diode parameters, expressions are derived for such useful converter properties as the load conditions necessary for circuit stability, the minimum noise figure, the maximum gain-bandwidth product, the necessary conditions for a positive mixer conductance at the radio frequency (r.f.) and intermediate frequency (i.f.) ports, and the pump loading necessary for self-excitation. It is shown that under proper conditions partial noise cancellation can occur because of correlation effects arising from the nonstationarity of the shot-noise process in the pumped diode. Most of the theoretical results are illustrated by the data obtained from a detailed numerical Fourier analysis applied to an actual high-frequency Esaki diode characteristic. These calculations show that the lowest noise figure and the highest gain-bandwidth product are obtained when the diode is biased in its negative conductance region.

An evaluation of GaAs FET oscillators and mixers for integrated front-end applications

An experimental evaluation of GaAs FETs as local oscillators and mixers at X-band will be reported, citing, as examples, FET mixers with gains in excess of 6 dB and oscillators with outputs exceeding 5 mW.

Physical principles of the esaki diode and some of its properties as a circuit element

Abstract A brief description is given of the physical mechanism underlying the operation of the recently invented, negative-resistance “tunnel” diode. This diode, which is capable of operation at microwave frequencies, is then analyzed from a circuit viewpoint. On the basis of this analysis, an equivalent circuit of the diode is obtained with the help of which are calculated such useful design criteria as the maximum frequency of oscillation and the maximum gain-bandwidth product, and the minimum noise figure, when the diode is used as an oscillator and amplifier, respectively. Experimental results are quoted which verify many of these quantities.

A two-stage all monolithic X-band power amplifier

An X-band amplifier which produces 565mW with 8dB gain (12dB small-signal gain), includes all bias and tuning circuits on-chip, and requires no bonding to a GaAs chip, will be discussed.

Network Synthesis for a Prescribed Impulse Response Using a Real‐Part Approximation

A semigraphical scheme is presented for the synthesis of a linear, finite, discrete network, in which the desired network response is prescribed in the time domain. The method is based on the approximation of the real part of a desired system function by a sequence of impulses along a contour parallel to the imaginary axis of the complex‐frequency plane. A simple scheme of error evaluation is proposed. Examples illustrating the synthesis procedure are also considered.