High-power generation in IMPATT devices in the 100-200-GHz range

A silicon double-drift IMPATT diode with high uniform doping levels was simulated. Simulation results show that it is possible for silicon IMPATT diodes to generate extremely high pulsed output power for frequencies above 100 GHz under high current-density operation. The highest output power matched to a 1-Ω load resistance obtained at 150 GHz is 37.7 W with a DC current density of 200 kA/cm², although the calculated power conversion efficiency is low. It is also shown that the low-power conversion efficiency limits the diode's continuous wave power operation     

X-band performance of GaAs power f.e.t.s

The results of X-band measurements on GaAs power f.e.t.s are reported. These devices are fabricated with a simple planar process. Devices with output powers of 1 W or more at 9 GHz with 4 dB gain have been fabricated from more than a dozen slices. The highest output powers observed with 4 dB gain are 1.78 W at 9 GHz and 2.5 W at 8 GHz. Devices have been operated with 46% power-added efficiency at 8 GHz.     

High-power c.w. transferred-electron oscillators

C.W. operation of high-power transferred-electron oscillators (t.e.o.s) is described. A maximum power output of 0.78 W at 8.7 GHz with an efficiency of 2.5% was obtained. This is believed to be the highest c.w. power output reported to date for a single t.e.o. in this frequency range. This high-power output is attributed to improved fabrication technology leading to a thermal resistance of only 8 deg C/W for a 0.015×0.015 in chip.     

11 GHz and 12 GHz multiwatt internal matching for power GaAs f.e.t.s

Multiwatt internal-matching techniques for multichip power GaAs f.e.t.s at 11 GHz and 12 GHz bands have been developed, adopting a lumped-element input circuit and a semidistributed output circuit. The internally matched device for the 11 GHz band exhibits 4 W power output with 3.4 dB associated gain, and the 12 GHz device 3.6 W power output with 3 dB associated gain.     

35 GHz GaAs power MESFETs and monolithic amplifiers

GaAs MESFETs optimized for power operation at 35 GHz are described. Various doping levels and potential barrier layers at the interface between the buffer and the active layers were studied. The best power performance was obtained from an FET on a very heavily doped active layer. A device on an AlGaAs heterobuffer had further improved output power. The best devices delivered output power densities of 0.8 W/mm with 23% efficiency, 0.71 W/mm with 34% efficiency, and 0.61 W/mm with 41% efficiency. Monolithic power amplifiers with a 400-μm FET generated 200 mW of output power. These amplifiers were monolithically power combined, resulting in 600 mW of output power at 34 GHz     

GaAs power m.e.s.f.e.t.s. with a graded recess structure

A new recess structure device was developed to improve the field distrubution and therfore the performance of GaAs power m.e.s.f.e.t.s. The linear gain and the output power were improved by 1?2 dB for this structure. The highest output powers obtained are 15 W with 4 dB associated gain at 6 GHz, and 4.3 W with 3 dB associated gain at 11 GHz.     

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.     

基于0.25μm GaAs PHEMT工艺的32GHz毫米波单片功率放大器

设计、制造和测试了基于0.25μm栅长GaAs工艺的32GHz毫米波单片功率放大器.该功率放大器采用三级放大,工作电压为6V,工作电流为600mA.带内最大小信号增益为17.4dB,在32GHz具有0.5W的饱和功率输出.     

A CW 4-W Ka-band power amplifier utilizing MMIC multichiptechnology

This paper describes a 28-GHz power amplifier with 4.5-W output power under CW operation. The amplifier utilizes four fully matched MMICs, in which 0.35-μm-long gate GaAs-based heterojunction FETs are employed. The developed power amplifier also provides a continuous-wave (CW) output power of 3 W over the bandwidth of 2 GHz at Ka-band     

High-power high-efficiency operation of read-type IMPATT-diode oscillators

C.W. operation of GaAs Schottky-barrier Read-type IMPATT-diode oscillators is reported. These devices exhibited efficiences from 20 to 24% with output powers of 2 ~ 3 W c.w. in the Ku-band. The best efficiency was 24%, with an output power of 1.8 W c.w., while the maximum output power was 3.2 W c.w., with an efficiency of 20.7% at frequencies near 14 GHz.     

InGaAs field-effect transistors with submicron gates forK-band applications

Depletion mode InGaAs microwave power MISFETs with 0.7 μm gate lengths and 0.2 mm gate widths have been fabricated using an epitaxial process. The devices employed a plasma deposited silicon dioxide gate insulator. The RF power performance at 18 GHz, 20 GHz, and 23 GHz is presented. An output power density of 1.04 W/mm with a corresponding power gain and power-added efficiency of 3.7 dB and 40%, respectively, was obtained at 18 GHz. This is the highest output power density obtained for an InGaAs based transistor on InP at K-band. Record output power densities for an InGaAs MISFET were also demonstrated to the stable within 3% over 17 hours of continuous operation at 18 GHz     

Development of 394.6 GHz CW Gyrotron (Gyrotron FU CW II) for DNP/Proton-NMR at 600 MHz

Gyrotron FU CW II with an 8 T liquid He free superconducting magnet, the second gyrotron of the THz Gyrotron FU CW Series, has been constructed and the operation test was successfully carried out. It will be used for enhancing the sensitivity of 600 MHz proton-NMR by use of Dynamic Nuclear Polarization (DNP). The designed operation mode of the gyrotron is TE_2,6 at the second harmonic. The corresponding frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE₀₆ mode, because of fabrication error of the diameter of the cavity. The operation is in complete CW at the output power of around 30 W or higher at the TE₀₆ cavity mode. There are many other operation modes at the fundamental and the second harmonic. Typical output power of the fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The highest frequency observed up to the present is 443.5 GHz at the second harmonic operation of TE_6,5 mode. The measured results are compared with the theoretical consideration.     

Millimeter-wave Gunn oscillator in series operation

The feasibility of series operation of a Gunn-diode oscillator in a millimeter-wave range is demonstrated. Oscillator output power and its dc-to-RF conversion efficiency can both be increased substantially by operating two Gunn diodes in series. Output power from two diodes in series operation is higher than twice the output power obtained from one individual diode. We report that the pulsed output power from two GaAs Gunn diodes in series operation reaches 4.4 W at a frequency of 33.2 GHz.     

Microwave Amplifier Using Several IMPATT Diodes in Parallel (Short Papers)

IMPATT diode amplifiers are described that use several packaged diodes in parallel in a coaxial housing. With a pair of GaAs Schottky-barrier diodes, a power output of 8 W (input locking power equals 300 mW) was obtained at 4 GHz without exceeding safe operating temperatures. Similarly, three-diode circuits produced 15 W (locking power equals 3.5 W) at 4 GHz and >10 W (locking power equals 2.7 W) at 6 GHz under safe operating conditions. The maximum power obtained from the pair was 11 W. The maximum power obtained from the 4 GHz three-diode circuit was 21 W. The efficiency of the diodes at the maximum power level was 12-13 percent. The characteristics of the pair are compared with those of the individual diodes and it is concluded that this power-combining scheme is very efficient and should be economically advantageous. The scheme permits the total diode area utilized in a single cavity to be increased significantly beyond that which is practical in a single diode package. The use of parallel operation permits efficient heat sinking of each diode package, which is impractical with series operation. The technique employed has been shown to be suitable for extension to three or more diodes for higher power. It is required that each set of diodes be matched for similar I-V characteristics. With this constraint, the close RF coupling of the diodes in conjunction with appropriate stabilizing resistor(s) assures that the diodes operate cooperatively as a unit capable of being powered from a single current-regulated source.     

GaAs m.e.s.f.e.t. linear power-amplifier stage giving 1 W

A balanced GaAs m.e.s.f.e.t. power stage has been developed for the 7?8 GHz satellite communication frequency band. At 7.5 GHz, the output power at 1 dB comparession 1 W with a power added efficiency of 37%. The small-signal gain was 6.65 ± 0.45 dB across the frequency band. The small-signal gain, phase, group delay and input and output v.s.w.r. as function of frequency are described. Large-signal gain saturation and 3rd-order intermodulation distrotion measurements are also presented.     

1.5-W CW S-band GaInP/GaAs/GaInP double heterojunction bipolartransistor

We report the first large-signal power result from a double heterojunction bipolar transistor (DHBT) based on the GaInP/GaAs/GaInP material system. A CW output power of 1.51 W and a power added efficiency of 52% were achieved at 3 GHz. Because the GaInP collector has a relatively high bandgap of 1.89 eV, high DC bias voltage operation with collector bias extending to 20 V (for a 40-V swing) is possible in this GaInP/GaAs/GaInP DHBT. This high DC bias voltage operation represents a unique advantage over the more conventional AlGaAs/GaAs HBT     

High-power pulsed GaAs double-drift hybrid-read impatt diodes for X-band

Gallium-arsenide double-drift hybrid-Read Impatt diodes have been developed to deliver high peak and average powers in X-band. A peak power output of 35 W with 20% efficiency has been obtained at 8.3 GHz for 20% duty cycle. Peak power output of 32 W with 20% efficiency has been obtained at 8·6 GHz for a 25% duty cycle. Peak power output of 26 W with 21.5% efficiency has been obtained at 8.6. GHz for 33% duty cycle.     

GaAs/AlGaAs heterojunction MISFET's having 1-W/mm power density at 18.5 GHz

The previously reported GaAs/AlGaAs heterojunction MISFET with an undoped AlGaAs layer as an insulator has been further optimized for power operation at upper Ku band. A 300-µm gate-width device generated 320 mW of output power with 33-percent efficiency at 18.5 GHz. The corresponding power density exceeds 1 W/mm. When optimized for efficiency, the device has achieved a power added efficiency of 43 percent at 19 GHz.     

A 4-9 GHz 10 W wideband power amplifier

A 4-9 GHz wideband high power amplifier is designed and fabricated, which has demonstrated saturated output power of 10 W covering 6-8 GHz band, and above 6 W over the other band. This PA module uses a bal-ance configuration, and presents power gain of 7.3 ± 0.9 dB over the whole 4-9 GHz band and 39% power-added efficiency (PAE) at 8 GHz. Both the input and output VSWR are also excellent, which are bellow -10 dB.     

Design, fabrication, and characterization of monolithic microwave GaAs power FET amplifiers

The design, fabrication, and characterization of three- and four-stage monolithic GaAs power FET amplifiers are described. Each of the amplifier chips measures 1 mm × 4 mm. Procedures for characterizing these monolithic amplifiers are outlined. Output powers of up to 1 W with 27-dB gain were achieved with a four-stage design near 9 GHz. The circuit topologies used were flexible enough to allow external bondwires to be used as shunt inductors for amplifier operation at C- or S-bands. An output power of 2 W with 28-dB gain and 36.6-percent power-added efficiency was achieved at 3.5 GHz, using a modified four-stage amplifier.