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Posts Tagged ‘complex’

Today, my paper on Tunable Mismatch Shaping for Quadrature Bandpass Delta-Sigma Data Converters was published in the Journal of Signal Processing Systems, Volume 65, Number 2, pp 199-210, November 2011.

From the abstract:

This paper presents an architecture for quadrature bandpass mismatch shaping that allows the center frequency of the mismatch suppression band to be tunable over the entire Nyquist range. The approach is based on the previously reported complex-valued tree-based mismatch shaper, and extends this to allow tunable operation. The proposed design has been implemented using VHDL and synthesized to logic gates. The hardware complexity and mismatch shaping performance of the proposed architecture are compared to that of a reference architecture, which uses separate tunable mismatch shapers for each complex component path. Simulation results show consistent mismatch shaping performance across the entire tuning range.

A pre-publication version of the paper can be downloaded here (pdf).

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This week, I presented a paper entitled Tunable Mismatch Shaping for Quadrature Bandpass Delta-Sigma Data Converters at the 2010 IEEE Workshop on Signal Processing Systems. This paper extends mismatch-shaping methods to quadrature data converters, and is co-authored with my doctoral advisor, Prof. Earl E. Swartzlander, Jr. The conference was held at the Cypress hotel in Cupertino, California. The presentation took place on Thursday, October 7, during Lecture Session 3: Application-Specific Signal Processing Architectures.

From the abstract:

Quadrature bandpass delta-sigma data converters are widely used in low-IF receiver applications where high linearity is required over a narrow bandwidth. A quadrature delta-sigma modulator with multibit quantization requires a digital-to-analog converter (DAC) for each of the in-phase (I) and quadrature (Q) paths. Device mismatch errors in the DAC can seriously degrade overall converter performance by adding I/Q path-mismatch and distortion. Mismatch noise shaping is an established technique for overcoming these limitations in a complex DAC, but usually anchors the signal band to a fixed frequency location. In order to apply mismatch shaping to applications that require tunable signal band locations, this paper presents a technique that allows the center frequency of the mismatch noise shaping transfer function through the complex DAC to be adjustable over the entire Nyquist range.

A pre-print version of the paper can be downloaded from here (pdf).

Edit-2011: The paper is now available on IEEExplore.

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Another paper has been accepted for presentation at the 2010 IEEE Workshop on Signal Processing Systems (SiPS), taking place in the San Francisco Bay Area, California, from October 6-8, 2010. Co-authored with my doctoral adviser, Prof. Earl E. Swartzlander, Jr., the paper is titled Tunable Mismatch Shaping for Quadrature Bandpass Delta-Sigma Data Converters.

This paper presents a technique that allows the center frequency of the mismatch noise shaping transfer function through a quadrature (complex-valued) bandpass delta-sigma DAC to be adjustable over the entire Nyquist range.

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