Methodology of Circuit Modeling of Charge-Sensitive Amplifiers Based on Wide-Band-Gap (GaAs, GaN) D-FETs

Semiconductors with wide bandgap are the main candidates in the foreseeable future for overcoming fundamental limitations of conventional electronics in high-temperature applications. The paper considers a step-by-step technique for selecting parameters and operating modes of GaAs, GaN charge-sensitive amplifiers based on depletion mode type Field Effect Transistor (D-FET), which provides minimum current consumption, low noise and high speed performance. Realization of the D-FETs on wide-band-gap semiconductors, for example, GaAs, GaN, allows to create microcircuits that retain their performance in hash operating conditions, including under the influence of penetrating radiation of high level and temperatures above 200°C. Modern technological routes of manufacturing of wide-gap microcircuits, usually, do not allow to form on one crystal active elements of several types and high-resistors, which complicates circuit synthesis of microcircuits of this class. The article gives recommendations on the development of design rules for analog microcircuits (operational and multidifferential operational amplifiers, transimpedance and charge-sensitive amplifiers, current conveyors, etc.) for the tasks of signal processing of sensors of physical quantities in the range of high temperatures (+150°C … +500°C). Circuit modeling using the proposed methodology allowed to develop a charge-sensitive amplifier that contains only GaAs DpHEMTs (double channel pseudomorphic high electron mobility transistor) of two designs and 8 kOhm resistor and has a power consumption of less than 55 mW, a rise time of less than 56 ns, the equivalent noise charge - less than 600 electrons at signal source capacitance of 100 pF.