W-band power combiners using double-drift IMPATTsilicon diodes have been developed to generate high pulsed power. The combiner design was based on a computer analysis of the cross-coupled coaxial-waveguide diode mounting structure which forms the basic module of the combiner. Peak output power of 20.5 W for a two diode combiner and 40 W for a four-diode combiner have been achieved. The diodes were operated at 100-ns pulsewidth and 0.5-percent duty cycle. The combiners demonstrated over 80-percent combining efficiency and 6-percent dc-RF conversion efficiency.

W-Band Power Combiner Design

The authors have developed a large-signal simulation technique extending an in-house small-signal simulation code for analyzing a 94 GHz double-drift region impact avalanche transit time device based on silicon with a non-sinusoidal voltage excitation and studied the effect of junction temperature between 300 and 550 K on the large-signal characteristics of the device for both continuous wave (CW) and pulsed modes of operation. Results show that the large-signal RF power output of the device in both CW and pulsed modes increases with the increase of voltage modulation factor up to 60%, but decreases sharply with further increase of voltage modulation factor for a particular junction temperature; while the same parameter increases with the increase of junction temperature for a particular voltage modulation factor. Heat sinks made of copper and type-IIA diamond are designed to carry out the steady-state and transient thermal analysis of the device operating in CW and pulsed modes respectively. Authors have adopted Olson's method to carry out the transient analysis of the device, which clearly establishes the superiority of type-IIA diamond over copper as the heat sink material of the device from the standpoint of the undesirable effect of frequency chirping due to thermal transients in the pulsed mode.

http://iopscience.iop.org/article/10.1088/1674-4926/34/2/024001/pdf

Effect of junction temperature on the large-signal properties of a 94 GHz silicon based double-drift region impact avalanche transit time device

In this paper large-signal modeling and simulation has been carried to study the frequency chirping due to temperature transients and the large-signal power and efficiency of pulsed silicon Double-Drift Region (DDR) Impact Avalanche Transit Time (IMPATT) device operating at 94 GHz. A large-signal simulation method based on non-sinusoidal voltage excitation incorporating the transient thermal effect has been developed by the authors. Results show that the device is capable of delivering a peak pulsed power output of 17.5 W with 12.8% efficiency when the voltage modulation is 60%. The maximum junction temperature rise is 350.2 K for a peak pulsed bias current of 6.79 A with 100 ns pulsewidth and 0.5 percent duty cycle; whereas the chirp bandwidth is 8.3 GHz.

Large-Signal Simulation of 94 GHz Pulsed Silicon DDR IMPATTs Including the Temperature Transient Effect

A high-power three-stage W-band injection-locked pulsed solid-state transmitter using four hybrid-coupled two-diode IMPATT power combiners as the final stage has been developed. Coherent peak output power of 63 W and 92.6 GHz was achieved. The transmitter was operated at 100-ns pulsewidth and 0.5-percent duty cycle. This transmitter development was directed at achieving a high-power output that would be useful for future miltimeter-wave system applications.

A 63-W W-Band Injection-Locked Pulsed Solid-State Transmitter

A high power three-stage W-band injection-locked pulsed solid state transmitter using four hybrid-coupled two-diode IMPATT power combiners as the final stage has been developed. Coherent peak output power of 63 W at 92.6 GHz has been achieved. The transmitter was operated at 100 ns pulsewidth and 0.5 percent duty cycle.

A 63 W W-Band Injection-Locked Pulsed Solid State Transmitter

High peak power oscillators using double-drift IMPATT diodes have been developed in W-band, The diodes were operated with 100 ns pulsewidth and 0.5 percent duty cycle. Peak power of 13 watts were consistently achieved. As a best result, over 15W peak power was achieved with selected diodes.

E.M. Nakaji

Papers

High Power 94-GHz Pulsed IMPATT Oscillators