Hybrid offset compensated latch-type sense amplifier for tri-gated FinFET technology

摘要

In this paper, a novel offset compensated latch-type sense amplifier consisting of hybrid (current & voltage) sensing operation is proposed for SRAMs. The offset compensation circuitry of the proposed sense amplifier includes FET based capacitors and current injection circuitry (CIC) for compensation against V-T mismatch of critical transistor pairs. The proposed amplifier does not cause extra overhead in SRAM access latency. The functionality of the proposed tri-gated FinFET sense amplifier in 20 nm technology is verified using 3D TCAD tool and its efficacy against V-T variability is tested with the help of HSPICE simulations. Reliability and performance characteristics of the proposed sense amplifier are compared with recently reported capacitor-based offset compensated sense amplifier (OCSA) and the conventional current-latched sense amplifier (CLSA). The proposed sense amplifier achieves 7.58% and 26.38% higher yield compared to OCSA and CLSA, respectively. In this study, the V-T mismatch in all critical transistor pairs of the sense amplifier was introduced simultaneously. The proposed amplifier outperforms OCSA and CLSA in the following: (i) 1.11 and 5.02 times higher offset tolerance, (ii) 1.66 and 2.66 times lower bit-line differential voltage (Delta V-in) to achieve target yield of 90%, and (iii) 16.84% and 52.94% lower standard deviation in sensing delay during read-0 operation due to higher offset tolerance. Effect of V(DD)scaling on yield and performance of various sense amplifiers is also evaluated. Under iso-area condition, the proposed sense amplifier exhibits 17.10% higher yield and x 2.55 higher offset tolerance in comparison with CLSA.