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Microwave devices
Published in Geoff Lewis, Communications Technology Handbook, 2013
TRAPPATT diode (trapped plasma avalanche triggered transit-time). The operation of this diode is based on an avalanche effect and the finite transit time of charge carriers. During part of the oscillatory cycle, a hole-electron plasma (collection of free electrically neutral carriers) is generated. An interaction takes place that results in a low field region being trapped between two high field regions. The diode is most useful as either an amplifier or an oscillator below about 10 GHz, where the longer drift region of the IMPATT diode generates heat dissipation problems. Oscillator power outputs in excess of 80 W at 5 GHz have been reported with amplification gain in excess of 5 dB.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Silicon bipolar transistors are used in most low noise oscillators below about 5GHz. HBTs are common today and extend the bipolar range to as high as 100GHz. These devices exhibit high gain and superior phase noise characteristics over most other semiconductor devices. For oscillator applications, complementary metal oxide semiconductor (CMOS) transistors are poor performers relative to bipolar transistors, but offer levels of integration that are superior to any other device technology. Above several GHz, compound semiconductor MESFETs and HEMTs become attractive for integrated circuit applications. Unfortunately, these devices tend to exhibit high phase-noise characteristics when used to fabricate oscillators. Transit time diodes are used at the highest frequencies where a solid-state device can be used. IMPATT and Gunn diodes are the most common types of transit time diodes available. The IMPATT diode produces power at frequencies approaching 400GHz, but the avalanche breakdown mechanism inherent to its operation causes the device to be very noisy. In contrast, Gunn diodes tend to exhibit very clean signals at frequencies as high as 100GHz.
Semiconductors
Published in Daniel D. Pollock, PHYSICAL PROPERTIES of MATERIALS for ENGINEERS 2ND EDITION, 2020
An IMPATT diode (IMPact, Avalanche, Transit-Time diode) consists of a DC, reverse-bias, p-n junction in which the reverse voltage is maintained at a level slightly less than that required for breakdown. It is placed in the circuit in such a way that a given time lapse occurs before the circuit reacts to avalanching.
Ka band noise comparison for Si, Ge, GaAs, InP, WzGaN, 4H-SiC-based IMPATT diode
Published in International Journal of Electronics Letters, 2019
Girish Chandra Ghivela, Joydeep Sengupta, Monojit Mitra
Recently, in microwave communication, impact avalanche and transit time (IMPATT) diode has emerged as the best alternative to bulky sized klystron and magnetron (as the source of microwave power generation and amplification) for the various applications. So, the analysis of IMPATT diode is more essential for microwave communication. Designers are concentrating on the best semiconductor materials for the optimised design of the diode. But due to the noise effect, practically less amplification of microwave signals is obtained from the IMPATTs (Sze & Ng, 2007, Chapter 9). Thus, it is important to do the noise analysis of the IMPATT diode. The noise associated in the avalanche region of IMPATT is resulting from the statistical variation in generation rates of electron and hole pairs (Sze & Ng, 2007, Chapter 9), which is limiting the application of IMPATT diode as microwave source (Eisele & Haddad, 1998, pp. 343–407). The small signal noise behaviour affects differently for different semiconducting materials. The noise analysis is carried out for silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), wurtzite gallium nitride (WzGan), and 4H-silicon carbide (4H-SiC)-based double drift region (DDR) IMPATT diode and comparison among them is presented. So, understating the noise generation mechanism and its behaviour at small signal conditions is very important in establishing optimised design and operating conditions for IMPATT diodes.
Estimation of power density in IMPATT using different materials
Published in International Journal of Electronics, 2020
Girish Chandra Ghivela, Joydeep Sengupta
Impact avalanche transit time (IMPATT) diode is a powerful solid-state semiconductor device that is used for generating sufficient power at frequencies of microwave, millimetre wave and sub-millimetre wave regions (Midford & Bernick, 1979). Presently, in the microwave frequency, the IMPATT (IMPact ionisation Avalanche Transit Time) diode is proven to be one of the most powerful solid-state sources. At millimetre wave frequency of 30–300 GHz, the IMPATT diode can able to generate highest continuous wave (cw) power output (Sze & Ng., 2007, Chapter 9). The main advantage of this microwave diode is high power capability compared to other microwave diodes (Ke-Lin & Swamy, 2010). The keys microwave applications of IMPATT diode includes alternative to bulky size of klystron (Chris & Balmer, 2008), as high power amplifier for wireless video communication, suitable for high power devices and photoconductive semiconductor switches, and also as excellent microwave generator for many applications. As the noise associated with the IMPATT diode is high (Ghivela, Sengupta, & Mitra, 2019a) and sensitive to operating conditions and the reactance is large, the diode may get over-heated and suffer burnout problem (Sze & Ng, 2007, Chapter 9). The aim of this work is to study the power density profiles for IMPATT so that burnout problem can be controlled with proper knowledge of maximum power withstand ability. In our analysis DC to RF power conversion efficiency of IMPATT diode is calculated through DC and small signal analysis. And the power-withstand ability (power density) of the IMPATT diode is studied and a comparison is being presented for Si, GaAs, Ge, WzGaN, InP and 4H-SiC. The reactance value strongly depends on oscillation amplitude of IMPATT diode (Sze & Ng, 2007, Chapter 9). Therefore, the small signal quality factor is also measured for different materials which represent the rate of growth of oscillation. Also, we have calculated the power density for different junction temperatures and modelled the heat sink with analysis of thermal resistances.