X- and Ku-band internally matched packaged GaAs f.e.t.

The design and performances of medium-power X- and Ku-band internally matched GaAs f.e.t.s are reported. With input-output v.s.w.r. lower than 2 : 1 over more than 20% bandwidth in the X-band and l0% in the Ku-band, 50 and 200 mW two-stage cascaded amplifiers have been realised with no matching circuit outside the packaged f.e.t. and with only one power supply.     

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.     

X and Ku band GaAs m.e.s.f.e.t.

A GaAs Schottky-barrier f.e.t. (m.e.s.f.e.t.) with a 1 ?m gate has been built, which is suitable for X band and Ku band applications. The unilateral power gain over the X band is above 9 dB and the noise figure is only 5 dB at 10 GHz.     

Simplified GaAs m.e.s.f.e.t. model to 10 GHz

A simplified design-oriented equivalent circuit for the GaAs m.e.s.f.e.t. is presented. Its relation to a common, but more complex, model is derived and characteristics are compared. Element values are easily determined from measurements, and the simple model shows good agreement with measured parameters to 10 GHz for 1 ?m-gate m.e.s.f.e.t.s.     

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.     

Low-temperature f.e.t. for low-power high-speed logic

A novel f.e.t. cooled to around 100 K is proposed. Detailed computer simulations support the conjecture of high-speed switching at low power levels with a power-delay product ? 10?14 J.     

High-speed 1 ?m GaAs m.e.s.f.e.t.

By minimising parasitic series resistances, a GaAs m.e.s.f.e.t. with 1 ?m gate length was fabricated, possessing the highest known r.f. power gain, measured up to 18 GHz, for GaAs m.e.s.f.e.t.s.     

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.     

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.     

Improvement of intermodulation distortion in microwave m.e.s.f.e.t. amplifiers using gate-bias compensation

A simple technique is described for improving the intermodulation distortion performance of microwave m.e.s.f.e.t. amplifiers. The technique utilises transistor gate-bias compensation controlled by the input signal level of the amplifier. For a constant output power of 0 dBm, an improvement in third-order intermodulation distortion product of up to 10 dB has been observed. The advantages and limitations of the technique are discussed.     

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.     

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.     

Experiments on integrated gallium-arsenide f.e.t. oscillators at X band

Experimental results obtained with GaAs f.e.t. oscillators at X band are described. It is demonstrated that the output power of f.e.t. oscillators is sufficient to drive X band mixers. The noise measure of these oscillators is competitive with Gunn devices, and can be reduced further.     

10-GHz 10-W Internally Matched Flip-Chip GaAs Power FET's

A newly developed internally matched configuration for a flip-chip GaAs power field effect transistor is presented. In this structure, gate and drain electrodes of the FET chips are directly connected to the lumped dielectric capacitors in the matching networks by thermocompression bonding using no wire. A power output of 10 W with 3-dB gain and a power added efficiency as high as 14 percent has been realized at 10 GHz.     

Effects of capacitance at crossover wirings in power GaAs m.e.s.f.e.t.s.

Power GaAs f.e.t.s. with an air-bridge crossover were compared with those of SiO2 crossover to find the effect of the capacitance at the crossover points. The capacitance of SiO2 crossover points is much smaller than that of the gate pad or the gate busbar in power GaAs f.e.t.s, and deterioration of the microwave performance due to that capacitance is negligible.     

Microwave power amplification with InP f.e.t.s

InP f.e.t.s were fabricated from v.p.e. layers, with an Al gate of 1.5 ?m × 308 ?m. The power output at 9 GHz, with 4 dB gain, was 1.15 W/mm gate width. This result is believed to be higher than the best published results obtained with equivalent GaAs f.e.t. structures.     

J.F.E.T. bucket-brigade circuit: some recent experimental results

A bucket-brigade circuit implementation with junction field-effect transistors (j.f.e.t.) offers a significant improvement in maximum data rates for digital operation, and in maximum bandwidth for analogue operation. Some 10-stage monolithic j.f.e.t. brigades have recently been built and successfully operated at data rates of 50 MHz. In the Letter, the j.f.e.t. structure is briefly described and some experimental results are presented.     

Simple model of large-signal properties of 1 W f.e.t. at 5 GHz

Extensive large-signal measurements performed on a 1 W microwave f.e.t. at 5 GHz verify that its added-power characteristics can be accurately predicted from a simple analytic model requiring only two large-signal measurements for each frequency of interest. This model makes possible the use of linear circuit theory to design broadband matching circuits for optimum added-power performance.     

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.     

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.