Partially-depleted Silicon-on-insulator CMOS Research Articles

Enhanced High Temperature Performance of PD-SOI MOSFETs in Analog Circuits Using Reverse Body Biasing

Analog circuits realized in a PD-SOI (partially-depleted silicon-on-insulator) CMOS technology for a wide temperature range up to 400°C are significantly affected by the transistor characteristics at high temperatures. As leakage currents increase with temperature, the analog device performance, for example, intrinsic gain and bandwidth, tend to decrease. Both effects influence the precision of analog circuits and lead to malfunction of the circuitry at high temperatures. Enhancement of the MOSFET device performance and improved design techniques are required to handle these issues. In this paper, we demonstrate that RBB (reverse body biasing) is a useful method to improve the analog performance of PD-SOI transistors and also to push the limit of analog circuit design in SOI technology beyond 300°C. It allows beneficial FD (fully depleted) device characteristics in a 1.0 μm PD-SOI CMOS technology by manipulating the depletion condition of the silicon film. Due to reduced leakage currents, operation in the moderate inversion region of the SOI transistor device up to 400°C is feasible. The method is verified by experimental results of transistors with an H-shaped gate (HGATE), an analog switch, current mirrors, a two-stage operational amplifier, and a bandgap voltage reference. The normalized leakage current of HGATE devices at high temperatures can be reduced by more than one order of magnitude. Thereby, the gm/Id factor is improved significantly especially in the moderate inversion region, which has been inaccessible due to leakage currents. As a result, the intrinsic gain of HGATE transistors is improved. As the method has also been applied to essential analog circuits, it has been found that RBB significantly reduces the errors related to leakage currents and enables the operation of analog circuits in PD-SOI technology up to 400°C.

Enhanced High Temperature Performance of PD-SOI MOSFETs in Analog Circuits Using Reverse Body Biasing

Analog circuit realized in a PD-SOI (Partially-Depleted Silicon-on-Insulator) CMOS process for a wide temperature range up to 400 °C are significantly affected by the MOSFET device characteristics at high temperatures. As leakage currents increase with temperature, the analog device performance, e.g. intrinsic gain and bandwidth tend to decrease. Both effects influence the precision of analog circuits and lead to malfunction of the circuitry at high temperatures. Enhancement of the MOSFET device performance and improved design techniques are required to handle these issues. In this paper, we demonstrate that reverse body biasing (RBB) is a useful method to improve the analog performance of PD-SOI transistors and also to push the limit of analog circuit design in SOI technology beyond 300 °C. It allows beneficial FD (fully depleted) device characteristics in a 1.0 μm PD-SOI CMOS process by manipulating the depletion condition of the silicon film. Due to reduced leakage currents, operation in the moderate inversion region of the SOI transistor device up to 400 °C is feasible. The method is verified by experimental results of transistors with an H-shaped gate (HGATE), an analog switch, basic current mirrors, a two-stage operational amplifier and a bandgap voltage reference. The normalized leakage current of HGATE devices at high temperatures can be reduced by more than one order of magnitude. Thereby the gm/Id factor is improved significantly especially in the moderate inversion region, which has been inaccessible due to leakage currents. As a result, the intrinsic gain of HGATE transistors is improved. The method has also been applied to basic analog circuits. It has been found that RBB significantly reduces the errors related to leakage currents and enables the operation of analog circuits in PD-SOI technology up to 400 °C.

Statistical timing and leakage power analysis of PD-SOI digital circuits

This paper presents a fast statistical static timing and leakage power analysis in Partially-Depleted Silicon-On-Insulator (PD-SOI) CMOS circuits in BSIMSOI3.2 100 nm technology. The proposed timing analysis considers floating body effect on the propagation delay for more accurate timing analysis in PD-SOI CMOS circuits. The accuracy of modeling the leakage power in PD-SOI CMOS circuits is improved by considering the interactions between the subthreshold leakage and the gate tunneling leakage, the stacking effect, the history effect, and the fanout effect. The proposed timing and leakage power analysis algorithms are implemented in Matlab, Hspice, and C language. The proposed methodology is applied to ISCAS85 benchmarks, and the results show that the error is within 5% compared with random simulation results.