Identifier

etd-043015-093200

Abstract

Scaling of CMOS to nanometer dimensions has enabled dramatic improvement in digital power efficiency, with lower VDD supply voltage and decreased power consumption for logic functions. However, most traditionally prevalent ADC architectures are not well suited to the lower VDD environment. The improvement in time resolution enabled by increased digital speeds naturally drives design toward time-domain architectures such as voltage-controlled-oscillator (VCO) based ADCs. The major obstacle in the VCO-based technique is linearizing the VCO voltage-to-frequency characteristic. Achieving signal-to-noise (SNR) performance better than -40dB requires some form of calibration, which can be realized by analog or digital techniques, or some combination. A further challenge is implementing calibration without degrading energy efficiency performance. This thesis project discusses a complete design of a 10 bit three stage ring VCO-based ADC. A lookup-table (LUT) digital correction technique enabled by the "Split ADC" calibration approach is presented suitable for linearization of the ADC. An improvement in the calibration algorithm is introduced to ensure LUT continuity. Measured results for a 10 bit 48.8-kSps ADC show INL improvement of 10X after calibration convergence.

Publisher

Worcester Polytechnic Institute

Degree Name

MS

Department

Electrical & Computer Engineering

Project Type

Thesis

Date Accepted

2015-04-30

Accessibility

Unrestricted

Subjects

linearization, Lookup-table, split ADC, votlage controlled oscillator, background calibration technique, Analog to digital converter, VCO-based ADC

Share

COinS