Date of Graduation

5-2022

Document Type

Thesis

Degree Name

Bachelor of Science in Electrical Engineering

Degree Level

Undergraduate

Department

Electrical Engineering

Advisor/Mentor

Mantooth, H. Alan

Abstract

This thesis details the design process of a bandgap voltage reference (BGR) integrated circuit in a 180 nm CMOS process. A BGR provides a constant DC voltage across a range of operating temperatures and supply voltages. By its nature, the circuit is intended as a reference, not to provide current, so the output would be connected to a very high impedance, such as the gate of a transistor. At 27°C, this design provides a 955 mV reference voltage given a nominal VDD of 3 V. From 20°C to 175°C, the output voltage has a variance of 7.2 mV (approximately 0.8%) at the nominal supply voltage. Also, when the supply voltage changes from 2 V to 3.6 V, the output voltage changes by 10.9 mV (approximately 1.1%). CTAT (complimentary to absolute temperature) and PTAT (proportional to absolute temperature) devices placed in series provide stability over temperature variation, and a differential amplifier provides feedback, stabilizing the output over changes in VDD.

Keywords

Bandgap voltage reference; circuits; output voltage; resistors; amplifier; negative feedback; supply voltage

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