A high power LSA relaxation oscillator

Active Microwave Semiconductor Devices

“…The highest CW power obtained from a TE diode is Q5 watt with 3% efficiency at 10 GHz (1 watt saoiurated output power when(45) operated as an amplifier). 50 GHz is probably the highest frequency one can expect from the transit time TIE device with 2 microns thickness which is the technological limit. (46) and tfrms values below 1Hz at 1MHz from the carrier (11 GHz) in a 1Hz bandwidth (Q=120).…”

“…Very impressive is 1 kwatt pulsed power obtained from a large volume LSA diode (49) with 10% efficiency. The optimum waveform is the"lrelaxationl"waveform first proposed by Jeppsson and Jeppesen (50). The LSA mode works only if the doping fluctuations within the diode are kept below 10-30% otherwise domains with extremely high fields form leading to distruction of the diode.…”

Some possible consequences of a transverse doping gradient in bulk-effect oscillators

“…, ~4 kv cm-1, is biased at just greater than threshold, the peak domain field attains any given value roughly 20-30% faster, during the transient period, than when no is constant. Therefore, in the series/hybrid mode (Jeppsson et al 1968, Yu et al 1968 where immature domains are used to achieve certain waveforms and phasing, a transverse doping gradient could well constitute the difference between efficient and inefficient operation, even for 'nolf' values in the correct rCgime. Finally, it is interesting to observe that changes in stable dynamics are also indicated.…”

Three decades of our graduate research and education in compound semiconductor materials and devices

“…Commercial bulk GaAs was given ohmic contacts and operated in the pulsed mode to limit over-heating. Peak power of -6KW in L band [1], and > 1 KW at X band were achieved using thick samples operating in the limited space-charge accumulation (LSA) mode in special cavities. Liquid phase epitaxy was then developed, allowing controlled doping of thick layers of n-type GaAs.…”

“…,N/GaN HEMT structures were then developed, with .30 < x < .35. These yielded 1 -1.3 x 10 13 /cm 2 electron sheet density, with up to 1,700 cm 2 /V-s electron mobility, [1][2] using the OMVPE reactor developed by Prof. J. Richard Shealy. This reactor used a single flow, single pressure, single temperature method, unlike the much more complex method developed earlier in Japan.…”