Gate Overdrive with Split-Circuit Biasing to Substitute for Body Biasing in FinFET and UTB FDSOI Circuits

Body biasing (BB) in bulk CMOS is an important tool for circuit designers that enables dynamic modulation of device thresholds post-fabrication, thus potentially improving yields, or allowing the circuit to adapt to different power modes, such as fully active or sleep. Fully-depleted silicon-on-insulator (FDSOI) FETs, such as ultrathin body (UTB) devices, may benefit from the same effect when the buried oxide (BOX) is thin enough to allow back plane biasing (BPB) to affect the accumulation or inversion in the channel. However, when the BOX is thick the back plane potential has very little effect on the channel, eliminating the ability to modulate threshold voltage via BPB. Similarly, FinFETs benefit very little from controlled body effect because the gate has nearly full control over the channel. In this paper a new circuit topology is presented which can act as a substitute for body biasing without relying on the body effect. The inputs, outputs, and supply rails are split in such a way that the gates of some devices are overdriven without increasing voltage swing, resulting in a higher Ion and reduced latency under forward bias, or reducing leakage current under reverse bias. For a 28nm FDSOI process a speedup of up to 15% can be realized under forward bias with an increase in power of 19%, while static power can be reduced by up to 35% with a 19% decrease in performance.