The accounting of the simultaneous exposure of the low temperatures and the penetrating radiation at the circuit simulation of the BiJFET analog interfaces of the sensors
The article considers a choice of CAD system and SPICE-models for the circuit simulation of characteristics of the bipolar (BiJFET) analog integrated circuits (IC) at the exposure of the penetrating radiation (PR) and the low temperatures. The authors suggest a modified SPICE-model, which describes the nonmonotonic change of the peak drain current and the slope of the p-n junction FET (JFET) within the temperature range from −200°C to 30°C.
Cryogenic transistor measurement and modeling for engineering applications
This article deals with the methodology of an electronic system design at liquid-helium temperatures. This technique includes the active device selection, characterization and simulation. Based on certain engineering criteria one commercial reference of SiGe heterojunction bipolar transistors is selected. Then, the technique of device characterization and measurement is considered. Typical output characteristics are given for this reference. All the tested devices of this reference are classified into three groups according to the presence of different low-temperature phenomena. An accurate and easy-to-use neural network model based on their experimental DC characteristics is proposed. This model is implemented in Agilent ADS Software, and the simulation results are compared with measurements in the course of the cryogenic amplifier design.
An Investigation of Negative Differential Resistance and Novel Collector–Current Kink Effects in SiGe HBTs Operating at Cryogenic Temperatures
In this paper, a new negative-differential-resistance (NDR) effect and a novel collector-current kink effect are investigated in the cryogenically operated SiGe heterojunction bipolar transistors (HBTs). Theory based on an enhanced positive-feedback mechanism associated with heterojunction barrier effect at deep cryogenic temperatures is proposed to explain both the observed NDR and the collector-current kink. The accumulated charge induced by the barrier effect acts at low temperatures to enhance the total collector-current, indirectly producing both phenomena. This theory is confirmed using the calibrated 2-D DESSIS simulations over temperature. These unique cryogenic effects also have significant impact on the ac performance of SiGe HBTs operating at high injection. Technology evolution plays an important role in determining the magnitude of the observed phenomena, and the scaling implications are addressed. In addition, the present NDR effect is also compared with previously reported NDR and hysteresis effects observed in highly scaled SiGe HBTs operating under forced-IB-base bias. The input drive condition of the transistor during its use in circuits, either under pure forced-current bias or under pure forced-voltage bias, or more practically, somewhere in between, determines the magnitude of the observed NDR and is of potential concern for circuit designers and must be carefully modeled