Improved mean power and long pulse width operation of InP t.e.o.s in J band

Irving, L.D.; Pattison, John E.; Braddock, P.W.; Gray, K.W.

doi:10.1049/el:19780079

Cited by 3 publications

(2 citation statements)

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“…It has been shown17 that the noise measure M approaches a limit q D(E) M Min kT p(E) (1) where q is the electronic charge, k is Boltzmann's constant, T is the absolute temperature, D(E) is the electron diffusion coefficient and p(E) is the differential negative mobility, both field dependent quantities. At approximately twice threshold field, D(E) of InP is only one -half that of GaAs.18 A low noise measure requires a low nL product and a uniform DC electric field over most of the device which can be achieved with a cathode notch structure1' as shown in Figure 7.…”

Section: Amplifiersmentioning

confidence: 99%

<title>New Indium Phosphide Sources</title>

Wandinger

1981

SPIE Proceedings

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The Indium Phosphide (InP) Gunn device is fast becoming a key component in the millimeter wave region.The device has superior performance as wideband low noise amplifier, low noise local oscillator, self-oscillating mixer, and low to medium power source. Its development and advances are primarily fueled by military systems requirements and developments covering missile and projectile guidance, high resolution radar systems, intercept secure communications and EW and ECM functions.In this paper an overview of the current status of indium phosphide Gunn device development and future trends is presented.Covered will be in particular key parameters leading to indium phosphide's advantage at millimeter -wave frequencies, recent material and device developments, oscillators, amplifiers and systems applications with emphasis on current capabilities.Other devices such as InP FET and InP IMPATT devices are not considered in this paper because of their current limitations to microwave frequencies.

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Section: Amplifiersmentioning

confidence: 99%

<title>New Indium Phosphide Sources</title>

Wandinger

1981

SPIE Proceedings

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“…In order to design the optimum resonator for this application, a model must be specified for the total frequency deviation during a pulse of given length Ti. Equation (6) describes an oscillator whose frequency changes at a rate appropriate to the unstabilised chirp rate (A fR) for one time constant of the resonator (tc) and at the stabilised rate for the remainder of the pulse, i. In order to stabilise an oscillator of given QEM and chirp rate, the resonator must have a locking range greater than the total frequency deviation over the whole pulse of the unstabilised oscillator.…”

Section: Rf Cirjuit Designmentioning

confidence: 99%

Fast Rise Time InP Oscillators Employing Cavity Stabilisation and Pulsed Priming Techniques

Smith

Tebbenham

1979

9th European Microwave Conference, 1979

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INTRODUCTIONThis paper describes the design of a fast rise time pulsed InP oscillator for operation at J-band. R.F. circuit techniques are described which simultaneously satisfy the conflicting requirements of a fast R.F. rise time and good frequency stability. R.F. CIRJUIT DESIGNThe R.F. circuit (see Figure 1) consists of a waveguide oscillator of the reaction cavity type. A single InP device is mnounted at the waveguide centroid on cylindrical posts. Experinentally it is observed that the loaded Q factor (QL) of this type of oscillator must be less than approximately 150 to achieve R.F. rise times faster than 5 nS, but the chirp is then greater than the required 3 MHz/300 nS. Although other methods of chirp reduction have been reported (1) in order to achieve the required stability over all environmental conditions cavity stabilisation techniques must be used. X Referring to Figure 1, a resonant cavity separated from the device by g/2 is iris-coupled in the waveguide broad-wall in the absorption mode. This method of coupling does not affect the basic oscillator rise time (2) since at the instant of switch-on the internal field in the resonant cavity is not established and no energy is stored. However, after a period of approximately three times the Q limited rise time of the resonant cavity, the amplitude of the internal field has reached its steady state value and the oscillator stability is then controlled by the resonant cavity. The design of the resonant cavity is treated in detail below but in outline the unloaded Q (QO) and the coupling iris size must be chosen such that the cavity QL is high enough to ensure adequate stability yet low enough such that its time constant is short compared with the pulse length. The oscillator is frequency stabilised over temperature as described by Myers and §tevens [3). The dF/dT of the oscillator, normally of the order -1 MHz/ C, is reduced by means of the compensatos to match or be less than that of the resonant cavity, typically -300 KHz/ C. Using this technique, chirp reduction has been maintained over the operational temperature range of -40 to +700C. The oscillator also incorporates a GaAs Schottky barrier detector diode, which provides the overall system with a monitor pulse within a few nanoseconds of the start of the R.F. pulse. The oscillator is fabricated in WG19 and fitted with a waveguide transformer feeding a WG18 isolator.The high efficiency InP pulsed device exhibits both a large delay between the application of the bias voltage and the start of the R.F. oscillations and an uncertainty in the magnitude of this delay. These are commonly referred to as switch-on delay and jitter respectively; measure-558 ments over a temperature range are shown for a typical device in Figure 2.The performance is better at higher temperatures but operation at peak efficiency is almost always accompanied by poor switch-on characteristics irrespective of ambient temperature. One solution to this problem is to employ phase priming techniques in which a small amount of power at a...

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High Efficiency Indium Phosphide Oscillators for Pulsed Applications

Chappell

Mailer

Brookbanks

1978

1978 8th European Microwave Conference

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High efficiency indium phosphide oscillators have been developed for pulsed applications in the 12 to 18 GHz frequency range. The development of low thermal resistance structures has enabled long pulse or high duty factor operation to be readily achieved. Individual devices have given peak powers of lOW at efficiencies of up to 17% and peak powers of 40W at efficiencies of greater than 10% have been obtained from multiple diode arrays. A cavity stabilised two diode array has given output powers of 1oW at 10% efficiency with less than 0.5 MHz chirp for irsec pulses. CW priming has been used to obtain minimal delay and jitter of the leading edge of the rf pulse and intraspectral line noise of -80 dbc/Hz. High efficiency indium phosphide transferred electron oscillators, which utilise the high dc to rf conversion efficiency properties of the current limiting two zone cathode E1], have been developed for use in the 12-18 GHz frequency range for pulsed applications. The current limiting cathode has the advantage that not only is the conversion efficiency increased but the rf impedance level is also raised so that large area devices can be readily matched into the circuit. To date peak powers of 20W have been obtained from single devices at efficiencies greater than 12% at a frequency of 15 GHz.For applications in which pulse lengths of less than lrsec and duty factors of less than 0.25% are employed the simple ?layer-upt device, in which the heat sinking is through the supporting InP substrate, is quite adequate provided the resulting frequency chirp (typically 50-100 MHz/rsec) can be tolerated. This chirp can be reduced by a factor of two or plating a lO m thick gold heat reservoir onto the cathode contact; power droop is also reduced by this technique. Thermal analysis of these two structures [2) shows that the observed transient temperature changes within the device can be described quite adequately by existing theories, in which the transient thermal impedance of the layer up device is typically .50C/W/ pAsec. A considerable improvement in the device thermal performance can be achieved if an integral heat sink (IHS) device is constructed L2,31 so that the heat generated within the active region is efficiently removed into the plated heat sink. In addition the rf performance is often improved due to the removal of the parasitic losses associated with the thick substrate of the layer up structure. An SEM photograph of a typical IHS device is shown in Fig8re 1. The transient thermal impedance for this structure is typically 0.3 C/W/pOsec giving chirp values of 10-20 MHz/Msec, with dc thermal impedances of better than 20°C/W allowing operation at both long pulse (up to 10r sec) and high duty factors (up to 5%) without performance degradation. The limiting feature in the long pulse or high Plessey Research (Caswell) Limited, Al-len Clark Research Centre, Caswell, Towcester, Northants. UK. 769 duty factor operation is thermal in that the increase in temperature associated with this mode of operation leads to increased d...

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Improved mean power and long pulse width operation of InP t.e.o.s in J band

Cited by 3 publications

References 1 publication

<title>New Indium Phosphide Sources</title>

<title>New Indium Phosphide Sources</title>

Fast Rise Time InP Oscillators Employing Cavity Stabilisation and Pulsed Priming Techniques

High Efficiency Indium Phosphide Oscillators for Pulsed Applications

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