M. Case

Active and nonlinear wave propagation devices in ultrafast electronics and optoelectronics

We describe active and nonlinear wave propagation devices for generation and detection of (sub)millimeter wave and (sub)picosecond signals. Shock-wave nonlinear transmission lines (NLTLs) generate /spl sim/4-V step functions with less than 0.7-ps fall times. NLTL-gated sampling circuits for signal measurement have attained over 700-GHz bandwidth. Soliton propagation on NLTLs is used for picosecond impulse generation and broadband millimeter-wave frequency multiplication. Picosecond pulses can also be generated on traveling-wave structures loaded by resonant tunneling diodes. Applications include integration of photodetectors with sampling circuits for picosecond optical waveform measurements and instrumentation for millimeter-wave waveform and network (circuit) measurements both on-wafer and in free space. General properties of linear and nonlinear distributed devices and circuits are reviewed, including gain-bandwidth limits, dispersive and nondispersive propagation, shock-wave formation, and soliton propagation. >

GaAs nonlinear transmission lines for picosecond pulse generation and millimeter-wave sampling

The GaAs nonlinear transmission line (NLTL) is a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky contacts. The engineering of functional monolithic NLTLs is considered. Through generation of shock waves on the NLTL, the authors have generated electrical step functions with approximately 5 V magnitude and less than 1.4 ps fall time. Diode sampling bridges strobed by NLTL shock-wave generators have attained bandwidths approaching 300 GHz and have applications in instruments for millimeter-wave waveform and network measurements. The authors discuss the circuit design and diode design requirements for picosecond NLTL shock-wave generators and NLTL-driven sampling circuits. >

A 60-watt X-band spatially combined solid-state amplifier

In this paper, we present our continued effort in the development of broadband spatial power combining systems implemented in a standard WR-90 waveguide environment. With sixteen commercial MMIC amplifiers integrated with tapered-slot antenna arrays, a new combining circuit renders a 61-watt maximum power output and a gain variation less than /spl plusmn/1.4 dB within the entire band of interest. Higher output power can be achieved by introducing more MMIC amplifiers but still maintaining the same circuit topology, thanks to the modular design of the spatial combiner.

112-GHz, 157-GHz, and 180-GHz InP HEMT traveling-wave amplifiers

We report traveling-wave amplifiers having 1-112 GHz bandwidth with 7 dB gain, and 1-157 GHz bandwidth with 5 dB gain. A third amplifier exhibited 5 dB gain and a 180 GHz high-frequency cutoff. The amplifiers were fabricated in a 0.1-/spl mu/m gate length InGaAs/InAlAs HEMT MIMIC technology. The use of gate-line capacitive-division, cascode gain cells and low-loss elevated coplanar waveguide lines have yielded record bandwidth broad-band amplifiers.

40-W CW broad-band spatial power combiner using dense finline arrays

This paper presents a broad-band spatial power-combining system based on tapered-slot antenna arrays integrated in a standard WR-90 waveguide environment. The system is designed using a modular tray architecture, providing full waveguide-band frequency coverage and an excellent thermal environment for a set of monolithic-microwave integrated-circuit (MMIC) amplifiers. The shape of the tapered-slot or finline structures was optimized to minimize return loss and provide a broad-band impedance transformation from the waveguide mode to the MMIC amplifiers. A prototype eight-element array using commercial GaAs MMIC power amplifiers yielded a maximum of 41 W output power (continuous wave) with a gain variation less than /spl plusmn/1.2 dB within the entire band of interest. The average combining efficiency over the operating band was estimated at 73%. The results suggest the efficacy of the design and a strong potential for higher powers by moving toward a greater number of MMICs per tray and a larger number of trays. Should the 100 W system be realized in the near future, our combiner system will become a promising candidate to challenge the dominant position currently claimed by the traveling-wave tube amplifiers.

28-39 GHz distributed harmonic generation on a soliton nonlinear transmission line

A second-harmonic generation is reported in the 26-40-GHz band through soliton propagation on a GaAs monolithic nonlinear transmission line. At 20-dBm input power, a 20-diode structure attained <12-dB conversion loss for input frequencies from 13.5-18 GHz, with 9.3-dB minimum conversion loss, while a 10-diode structure attained <12-dB loss, 14-19.5 GHz (7.3-dB minimum). With reduction of conductor skin losses, broadband operation and peak conversion efficiencies approaching -3 dB are attainable.<<ETX>>

V-band and W-band broad-band, monolithic distributed frequency multipliers

Broadband V-band and W-band frequency multiplication is reported using soliton propagation on a GaAs monolithic device. With 24-dBm input, a doubler attained 17.4-dBm peak output power with at least a 52-63.1-GHz, 3-dB bandwidth, and a tripler attained 12.8-dBm peak output power with at least a 81-108.8-GHz, 3-dB bandwidth. These multipliers, fabricated with 3- mu m design rules on GaAs and driven by lower-frequency amplifiers. have applications as cost-effective sources in millimeter-wave systems. >

Millimeter-wave on-wafer waveform and network measurements using active probes

We have fabricated active probes for on-wafer waveform and network measurements. The probes incorporate GaAs nonlinear transmission line (NLTL) based network analyzer (NWA) integrated circuits and low-loss quartz coplanar-waveguide probe tips. The active probes show step response falltimes of 2.7 ps when excited by a 0.7-ps falltime input, Using these active probes, we demonstrate both waveform measurements with 2.7-ps risetime and network measurements to 200 GHz. We discuss the probe tip and NWA IC design, the hybrid assembly and mechanical design, and system design considerations. On-wafer waveform and S-parameter measurements of monolithic millimeter-wave integrated circuits are demonstrated. >

A time-domain millimeter-wave vector network analyzer

A millimeter-wave vector network analyzer is implemented with a monolithic GaAs directional time-domain reflectometer integrated circuit mounted directly on a microwave wafer probe. The vector network analyzer performs on-wafer network analysis up to 96 GHz with +or-1 dB accuracy.<<ETX>>

Impulse compression using soliton effects in a monolithic GaAs circuit

A monolithic GaAs impulse compressor circuit which utilizes soliton wave propagation effects in nonlinear transmission lines has been fabricated. The circuits compress a 20 dBm, 8 GHz sinusoid to a train of 3.9 V peak to peak, 5.5 ps full width at half maximum impulses.