A Complementary Positive Feedback-Assisted Current Mirror-Based Level Shifter for Energy-Efficient Level Conversion for Wide Voltage Ranges

A complementary positive feedback-assisted current mirror-based level shifter (CPFLS) is proposed to reliably convert subthreshold signals to higher voltages. By adopting a positive feedback structure, the CPFLS mitigates the delay degradation and short-circuit current issues inherent in a prior art, WCMLS, due to its negative feedback design. Additionally, the CPFLS addresses the instability caused by the dynamic node in the CMLS-LED by incorporating a current-limiting circuit. Moreover, the CPFLS effectively prevents the delay degradation observed in diode-MOSFET insertion-type LSs with split-controlled inverter, when the voltage difference between the input and output is small, leveraging its positive feedback structure to maintain fast and stable operation. The measurement results from a test chip fabricated in 28-nm CMOS technology demonstrate that the CPFLS successfully converts a 0.28-V input signal to a 1.0-V nominal voltage with stable operation, achieving an 89% improvement in the measured delay compared to WCMLS. Furthermore, the CPFLS achieves up to 53%/75% faster measured delay and 63%/89% better energy-delay product (EDP) than the split-level converter (SLC) at V${}_{\mathrm {DDH}} = 1.0$/0.7 V, respectively.