Design of Low-Voltage Current Mirrors using Flipped Voltage Follower Cell

Abstract

The desire for portability of electronics equipment generated a need for low votage/ low power system in battery products like hearing aids, implantable cardiac pacemakers, cell phones and hand held multimedia terminals. The dissertation discusses the basic cell known as “Flipped voltage follower” for low voltage/low power operation and includes the benefits of flipped voltage follower over conventional voltage follower. In this work, a new low-voltage current mirror (LVCM) is proposed. The circuit has low power supply requirement of 1.2V, wide input current range of 0-100μA, low DC error of 5.7%, low DC power dissipation of 111.20μW and low input impedance of 14.1 KΩ. Flipped voltage follower based low-voltage current mirror I (FVFLVCM I) has also been proposed to reduce voltage supply requirement of the current mirror. The proposed FVFLVCM I has wide input current range of 0-50μA, low DC error of 2.26%, low DC power dissipation of 36.74μW, low input impedance of 1.84 KΩ and low voltage supply requirement of 1V. In addition, the flipped voltage follower based low-voltage current mirror II (FVFLVCM II) has been proposed in order to improve input current range, DC error and bandwidth. The FVFLVCM II has low power supply requirement of 1.2V, wide input current range of 0-150μA, low DC error of 3.7%, low DC power dissipation of 99.40μW, high bandwidth of 629MHz and low input impedance of 30.08 KΩ. The stability of the proposed circuits has been performed by time-domain approach and frequency domain approach using Routh-Hurwitz stability criteria and phase margin calculations, respectively. The bandwidth of all the proposed current mirrors has also been enhanced using resistive and active compensation techniques. The applications such as LDPC decoder, adder and subtractor are also designed. The results have been simulated using SPICE in the TSMC 0.18 μm CMOS technology and are presented to validate the effectiveness of the proposed current mirrors.