Ku- and K-band internally matched high-power GaAs f.e.t. amplifiers

Internal-matching techniques, using lumped-element capacitors fabricated on high dielectric ceramics, have been developed for high power GaAs f.e.t.s in Ku- and K-bands. The developed internally matched high-power f.e.t. amplifier modules have exhibited 1.9 W power output with 4 dB associated gain at 14 GHz and 1.25 W power output with 3 dB associated gain at 18 GHz.     

Flip-chip mounted GaAs power f.e.t. with improved performance in X- to Ku-band

A GaAs power m.e.s.f.e.t. with a new structure has been developed, which allows extremely reduced source inductances and minimised thermal resistance. In the structure, the chip, with metal posts plated on the source, drain and gate pads, is connected directly to the package with no wire. The best results obtained were 2.5 W at 15 GHz and 4.1 W at 12 GHz.     

10 GHz/10 W internally matched flip-chip GaAs power f.e.t.s

A flip-chip GaAs power f.e.t. delivering 10 W power output with 3 dB gain has been realised at 10 GHz by using a newly developed internal matching technique, in which the f.e.t. chips are directly connected to the lumped capacitors in the matching networks.     

Common-gate GaAs f.e.t. oscillator

Frequency tuning, power and noise characteristics of a common-gate GaAs f.e.t. oscillator were investigated. By changing the common-gate lead inductance, the frequency was changed by almost two octaves. The f.m. noise of the low-Q factor f.e.t. oscillator was at the same level as that of a medium-Q factor GaAs impatt oscillator.     

Broadband varactor-tuned GaAs f.e.t. oscillator

A broadband varactor-tuned GaAs f.e.t. oscillator (7.4 to 13.1 GHz) is presented, together with measured and predicted performance characteristics. The circuit uses tuning in series with both the gate and the source leads of the device to maintain optimum oscillation conditions across the band.     

Monolithic broadband GaAs f.e.t. amplifiers

A unique monolithic X-band f.e.t. amplifier is described. Wideband matching circuits, using lumped elements, are integrated with the transistor on semi-insulating gallium arsenide to produce an amplifier chip 1.8×1.2 mm. Gains in excess of 4.5 dB over 7.5 to 11.5 GHz have been measured. The chip has been installed into a low-parasitic package to produce a gain module suitable for the microwave engineer.     

GaAs f.e.t.s with silicon-implanted channels

Field-effect transistors with channel doping profiles fabricated by the implantation of silicon ions into high-resistivity vapour phase epitaxial GaAs have given noise figures of 2.9 dB with an associated gain of approximately 5 dB at 10 GHz. Similar measurements on F.E.T.S fabricated in an identical manner, except for the channel fabrication, where silicon ions were implanted directly into a Cr-doped semi-insulating GaAs substrate, have resulted in nose figures typically 1 dB higher.     

Performance of sulphur-ion-implanted GaAs f.e.t.s

GaAs f.e.t.s have been produced by sulphur-ion implantation that give optimum noise figures as low as 4.6 dB at 10 GHz and maximum available gains of greater than 10 dB at 10 GHz. A considerable degree of uniformity among the devices is observed.     

Tunable X band GaAs f.e.t. amplifier

The design of a frequency-tunable X band amplifier using GaAs Schottky field-effect transistors is described. By using a broadband input matching circuit and a frequency-tunable output matching circuit, the gain of 7±0.5 dB obtained from a single-stage amplifier may be varied from 8 to 10 GHz, with corresponding terminal v.s.w.r.s, over any 600 MHz band width, better than 2:1. A single-stage amplifier gives a noise figure of 4.7 dB with a gain of 5.8 dB, and a 2-stage amplifier a 6.0 dB noise figure with 12.5 dB power gain.     

Performance of selenium-ion-implanted GaAs f.e.t.s

Selenium-ion-implanted GaAs f.e.t.s have given minimum noise figures as low as 3·4 dB and maximum available gains of at least 10 dB at 10 GHz. The devices do not appear to suffer from short-term drift problems, and have greater device-characteristic uniformity and reproducibility than epitaxial f.e.t.s.     

Light-induced effects in GaAs f.e.t.s

It is shown theoretically and experimentally that the variations of the d.c. and dynamic properties in a GaAs f.e.t. when a light beam strikes the transistor's gate can be accounted for by an appropriate change in the gate-junction equivalent built-in voltage. A simple relationship connects this change with the variations of the light intensity.     

Ion-implanted GaAs X-band power f.e.t.s

Active layers for GaAs power f.e.t.s have been produced by Si implantation into Cr-doped substrates followed by a simple proximity-annealing technique. Devices fabricated on these layers have up to 1.05 W/mm gate width at 10 GHz. This performance is equal to that of epitaxial devices.     

High-efficiency GaAs m.e.s.f.e.t. amplifiers

High-efficiency c.w. amplification with GaAs m.e.s.f.e.t.s under class-B conditions has been demonstrated. Power added efficiencies as high as 68% at 4 GHz and 41% at 8 GHz have been achieved. Two-tone tests were carried out at 4 GHz. The power added efficiencies at the 3rd-order intermodulation levels of ?20, ?25 and ?30 dB were 49, 40 and 35% respectively.     

Low-noise GaAs m.e.s.f.e.t.s

GaAs m.e.s.f.e.t.s with optimum noise figures of 1.6 dB at 6 GHz have been fabricated by projection photolithography. An equation has been developed for the calculation of optimum noise figure which gives good agreement between calculated and measured values.     

GaAs power f.e.t.s with semi-insulated gates

GaAs semi-insulated-gate f.e.t.s (s.i.g.f.e.t.s) have been fabricated by Ar+ bombardment in the gate region. The d c. characteristics and microwave performance are compared with those of conventional power m.e.s.f.e.t.s fabricated from the same slice. Up to 2.9W output power with 4dB gain has been obtained from s.i.g.f.e.t. devices at 8 GHz.     

High peripheral power density GaAs f.e.t. oscillator

Peripheral power density (p.p.d.), i.e. the output power per Unit gate width is defined as a figure of merit for GaAs f.e.t. oscillators. An X-band oscillator circuit using series and shunt feedback is described and its performance characteristies indicated. It is shown that this GaAs f.e.t. oscillator circuit configuration has the highest peripheral power density.     

Alumina microstrip GaAs f.e.t. 11 GHz oscillator

A small, lightweight 11 GHz f.e.t. oscillator has been developed. An output power of 10 mW with an efficiency of 10% was easily produced using a GaAs f.e.t. designed for small-signal amplifier applications. Its low power consumption makes it a suitable low-noise source for integrated-receiver applications.     

Capacitor-coupled logic using GaAs depletion-mode f.e.t.s

A new method of interconnecting depletion-mode GaAs f.e.t. logic stages, using capacitive coupling, eliminates the need for a negative power supply and is more tolerant of processing spreads, particularly of pinch-off voltage. The technique may be combined with conventional level shifting, operating at very low current. The use of capacitance may be extended to achieve clocked dynamic data storage with very low power dissipation.     

High efficiency GaAs Schottky-barrier gate f.e.t. oscillator

A high efficiency high p.p.d. GaAs f.e.t. oscillator was developed. An output power of 63 mW with an efficiency of 39.7% and a p.p.d. of 0.21 mW/?m was easily produced at 9.3 GHz using a HP FET 1101 A-HPAC 100 A. The design of this oscillator was effected using a large signal method by means of a time-domain analysis program IMAG III, which computes the transient response of a nonlinear f.e.t. network.