Low Voltage Bandgap Reference
Bandgap references (BGREFs) are used in computer systems to generate precise reference voltages. These are used as references to generate the supply voltages of the CPU's. In addition reference voltages are required for many other applications, such as analog-to-digital converters (ADC), Audio, Voice, Clock generation and a host of other applications.
In the case of the CPU's, the accuracy of the supply voltage is very important for low-power applications, since there is a direct correlation between voltage and power.
This project involves designing a bandgap reference which operates at very low supply voltage (0.5-0.7V) and still generates an accurate reference close to this supply rail. Bandgap references require forward biased diodes, whose voltage is ~ 0.7V at room temperature, so generating a good bandgap reference at lower voltages than the diode is a challenge.
There are several techniques which can be used to accomplish this, so more that 1 student can attempt this project.
The students are expected to read and understand several papers about bandgap references. The BGREFs will be designed and simulated using cadence tools. Once the circuit is ready, layout will be done, so that the circuit can be prepared for tapeout. The conclusion of the project involves a design review, including post-layout extraction studies.
Good understanding of Linear Circuits - 83-303
Basic Analog Circuits - 83611 is preferred, but not required.
1) H. Banba, et. al. “A CMOS Bandgap Reference Circuit with Sub-1-V Operation” in IEEE J. Solid-State Circuits, 34, 5, MAY 1999. p. 670.
2) A 32nW Bandgap Reference Voltage Operational from 0.5V Supply for Ultra-Low Power Systems, Aatmesh Shrivastava, International Solid State Circuits Conference, ISSCC 2015, Digest of Technical Papers.