A Fully Static True-Single-Phase-Clocked Dual-Edge-Triggered Flip-Flop for Near-Threshold Voltage Operation in IoT Applications

Abstract

A Dual-Edge-Triggered (DET) flip-flop (FF) that can reliably operate at low voltage is proposed in this paper. Unlike the conventional Single-Edge-Triggered (SET) flip-flops, DET-FFs can improve energy efficiency by latching input data at both clock edges. When combined with aggressive voltage scaling, significant efficiency improvement is expected. However, prior DET-FF designs were susceptible to Process, Voltage and Temperature (PVT) variations, limiting their operation at low voltage regimes. A fully static true-single-phase-clocked DET-FF is proposed to achieve reliable operation at voltages as low as a near-threshold regime. Instead of the two-phase or pulsed clocking scheme in conventional DET-FFs, a True-Single-Phase-Clocking (TSPC) scheme is adopted to overcome clock overlap issues and enable low-power operation. Fully static implementation also enables robust operation in a low voltage regime. The proposed DET-FF is designed in 28nm CMOS technology, and a comprehensive analysis including post-layout Monte Carlo simulation for wide PVT ranges is performed to validate the design approaches. Extensive analysis and comparison with prior-art DET-FFs confirmed that the proposed DET-FF can operate at the lowest voltage of 0.28 V for a temperature range of -40 °C to 120 °C while maintaining nearly-best energy efficiency and power-delay-product.

Keywords

• Flip-flop
• dual-edge-triggered (DET)
• single phase
• low power
• near-threshold voltage