Analog-to-digital conversion via duty-cycle modulation
- 1 January 1997
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing
- Vol. 44 (11) , 907-914
- https://doi.org/10.1109/82.644044
Abstract
An exchange of the amplitude axis for the time axis offers a possibility of overcoming resolution problems in analog-to-digital conversion in low-voltage CMOS circuits and/or of circumventing special resistor options in silicided processes. This exchange can be effected via some form of duty-cycle modulation. For its implementation a circuit configuration is described, consisting of an asynchronous sigma-delta modulator, followed by a phase-synchronized tapped ring oscillator which produces a poly-phase signal for sampling the asynchronous signal at a relatively low frequency. A detailed analysis is presented which accurately predicts the properties of the conversion scheme with respect to aliasing, quantization noise and nonlinear distortion. The results are illustrated with simulations of a design exampleKeywords
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