On-Chip Measurement of Bandgap Reference Voltage using a Small Form Factor VCO Based Zoom-in ADC
Osman Emir Erol1, Sule Ozev1, Chandra Suresh2, Rubin Parekhji3 and Lakshmanan Balasubramanian3
1Department of Electrical Engineering, Arizona State University, Tempe, AZ, USA
2Department of Electrical and Computer Engineering NYU Abu Dhabi, Abu Dhabi, UAE
3Texas Instruments India
A robust and scalable technique for measuring the output voltage of a band-gap reference (BGR) circuit is described. The proposed technique is based on an ADC architecture that uses a voltage controlled oscillator (VCO) for voltage to frequency conversion. During production testing, an external voltage reference is used to approximate the voltage/frequency characteristics of the VCO with 5ms test time. The proposed zoom-in ADC approach is manufactured with 0.5µm CMOS process. Measurement results indicate that 12 bits of resolution within the measurement range can be achieved with the zoom-in approach. Worst-case INL for the ADC is less than 0.25LSB (50µV).
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