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The authors report the third-order intermodulation distortion and phase deviation of 1.2-mm periphery double pulsed doped pseudomorphic high-electron-mobility transistors (HEMTs) at high levels of power and efficiency. A device tuned for single-tone power-added efficiency (PAE) of 59% with 0.87-W output power and 10.4 associated gain at 10 GHz could provide two-tone PAE of 50% with -19 dBc IM3/C and 0.30 W/tone. Single-tone phase deviation never exceeded 18 degrees from small signal with a phase deviation slope less than 3 degrees /dB. These measurements compare favorably to those of reported GaAs-based devices with comparable output power. A dry etched double recess structure was incorporated in the device for obtaining high reverse breakdown voltage and therefore high efficiency. >

A millimeter-wave monolithic two-stage matrix distributed amplifier with greater than 11-dB gain from 16 to 38 GHz has been demonstrated. The two-stage matrix amplifier described here extends the matrix amplifier to millimeter-wave frequencies. The matrix amplifier topology yields a compact circuit with higher gain per unit area than a conventional distributed amplifier. >

A number of GaAs transistors were evaluated as passive mode mixers with a 10 GHz RF and 2 GHz IF. Both single-tone and two-tone performance were measured for an ion implanted MESFET, spike-doped PsMESFET, a power PsHEMT and a npn power HBT. All were shown to have a substantially lower distortion than a comparable diode mixer. One transistor, the spike-doped PsMESFET, has a relative third order intercept point 20 dB higher than that of a diode mixer. >

A technique has been developed for modeling intermodulation distortion of GaAs MESFETs using pulsed I-V drain characteristics. The technique involves measuring the drain I-V characteristic using short drain and gate pulses from a DC operating point. This pulsed I-V characteristic is used to model the nonlinearity of the drain current source. In addition, S-parameters measured about the DC bias point are used to model the gate capacitance nonlinearity. These nonlinearities are combined into a single model, and the harmonic balance method is used to simulate intermodulation performance. This technique has been used to simulate the third-order intermodulation distortion of a spike-doped MESFET and to investigate sensitivities of source and load impedance and device nonlinearities on intermodulation performance. >

The design, fabrication, and performance of a 6-18 GHz, 2*5 bidirectional matrix distributed amplifier is described. This amplifier, having two bidirectional distributed amplifier chains stacked together, shares the same gain elements in both the transmit and receive directions. The amplifier has shown >10 dB gain with better than +or-0.5 dB of gain tracking and +or-5.0 degrees of phase tracking between the transmit and receive directions over the 7-17 GHz frequency band. In addition, the biasing scheme of this amplifier enables the stages to be connected in cascade at RF frequencies and in cascode for DC biasing, thus conserving current. >

A highly linear GaAs MESFET has been developed. This device incorporates a spike profile in its active channel and was designed specifically for linearity. A third-order intercept (IP3) and a 1 dB compression power of 43 dBm and 19 dBm, respectively, have been measured on a 400 mu m device at 10 GHz. The difference between these two numbers, 24 dB, is the largest yet reported for a MESFET. This device also dissipates only 400 mW of DC power yielding a linearity figure-of-merit (IP3/P/sub DC/) of 50. >

We report design, fabrication, and test of a monolithic GaAs IC implementing a broadband optically-driven digital/analog RF interface. The circuit operates in an asynchronous mode to detect AM digital and RF on a single optical fiber input, control RF level, and transmit the RF to the output. >

The above document by Fardon et al, listed in this issue's Table of Contents with links to the full versions recently published by Spine and [The Spine Journal][1] , represents an update to the original article coauthored by David Fardon, MD, and Pierre Milette, MD, entitled “Nomenclature and

A single-chip 2-20-GHz transmit/receive (T/R) module has been fabricated. This monolithic microwave IC (MMIC) includes a four-stage power amplifier chain, a four-stage low-noise amplifier, chain, and two T/R switches. A selective ion implantation process was used. One implant profile was optimized for low-noise operation and a second was optimized for power performance. All the circuits were designed to be relatively insensitive to process variations, thereby ensuring adequate yield despite the complexity of the chip. Distributed amplifiers are used throughout, and the T/R switches use a standard series-shunt FET configuration. All circuits have been miniaturized to keep the total chip size small. The entire T/R circuit measures only 0.143 in*0.193 in (3.6 mm*4.9 mm). >