A First Approach in Using Super-Steep-Subthreshold-Slope Field-Effect Transistors in Ultra-Low Power Analog Design

The benefits of steep-Subthreshold Swing (SS) devices, though plentiful at the device-level, have yet to be fully exploited at the circuit-level. This is evident from a look at the Three-Independent-Gate Field-Effect Transistor (TIGFET), a device renowned for its ability for polarity reconfiguration. At the same time, its demonstrated dynamic control of the subthreshold slope beyond the thermal limit has only been studied at the device-level. This latter benefit is referred to as Super-Steep Subthreshold Slope (S4) operation and can lead to unprecedented gain, which is ideal for use in an amplifier circuit. In this book chapter, we investigate the impact of S4 operations when designing differential-amplifier circuits while using TIGFET technology. We demonstrate the benefits of our implementation both from a theoretical standpoint and through circuit-level analyses. More specifically, we show that the TIGFET-based amplifier gain is 95.5x better, and that the gain-bandwidth product is improved by 13.8x, compared to an equivalent MOSFET-based design at the 90 nm node. Besides, we show that at equivalent gains, the TIGFET-based amplifier decreases the area and power by 22.8x and 7.2x, respectively, against its MOSFET counterpart. Further investigations prove that TIGFETs could be used in biosensing application where noise and power consumption are crucial. We have demonstrated that the use of TIGFETs could improve the thermal noise of low-power, Low-Noise Amplifiers (LNA) by 83% and the noise efficiency factor (NEF) by 58%.