CJFET Op-Amp without Current Mirrors for Low Temperature Applications

This paper proposes operational amplifier’s (Op-Amps) architectures based on complementary field-effect transistors with p-n junction (CJFETs), in which the effect of channel length modulation on the systematic component of the Op-Amp’s zero offset voltage (Voff) is reduced. The peculiarity of the developed Op-Amp’s circuitry solutions is that due to the high self-adjusting symmetry of the static mode in terms of the gate-drain voltages of the dominant CJFETs, they provide a low Voff level and increased values of the gain (GAIN). The computer simulation of Op-Amps in the LTSpice software (Analog Device, USA) showed that GAIN of the Op-Amps is more than 80 dB, and the systematic component of the zero offset voltage is within 30 μV in the temperature range up to -197°C. Op-Amp circuits of the proposed subclass can have low current consumption in static mode and can be performed not only on Si CJFETs, but also on the basis of wide-gap semiconductors (SiC CJFET, GaN CJFET or GaAs CJFET). Recommended applications of the developed architectures are analog interfaces of physical quantities of sensors for high-energy physics, medicine, and space instrumentation.