1V Differential Input Stage with Bulk-Driven Current Mirror for Low-Voltage Operational Amplifier

Objectives:This paper presents the design and analysis of differential input stage to design low voltage operational amplifier, where bulk-driven MOSFETs are incorporated in the current mirror.Methods/Analysis: To be possible to operate circuit at lower supply voltage, body-driven transistorsare used to design current mirror. Circuit is designed using 180nm (Complementary Metal Oxide Semiconductor) CMOS n-well technology and BSIM 3v3 Specter models are used to analyze the design. Performance parameters are validated by simulations. Findings: The amplifier shows DC openloop gain of 44 dB. The Unity Gain Bandwidth (UGB) is 3.3 MHz with a phase margin of 87.8°. The amplifier exhibits Common-Mode Rejection Ratio (CMRR) of 62 dB. The input referred spot noise voltage at 1KHz is 42.46nV/√Hz. These results are obtained with a supply voltage of 1V. Average power consumption of the amplifier is 36.36 μW under 10 pF load condition, which makes it suitable for low voltage and low power applications. Improvement: Gain can be further improved by employing cascade current mirror in the presented amplifier as it will increase output impedance.