Title:
DIGITAL NON-INTEGER SAMPLE/HOLD IMPLEMENTED USING VIRTUAL FILTERING
Document Type and Number:
WIPO Patent Application WO2008005151
Kind Code:
A8
Abstract:
A method and apparatus for implementing non-integer sample hold operations in a sigma-delta digital-to-analog converter system includes an interpolation filter, a polyphase filter circuit, and a modulator. The polyphase filter circuit is used to virtual upsample a digital input signal by a predetermined non-integer upsample ratio of a relatively large number. The polyphase filter circuit is formed of a long zero-order hold and a short FIR filter so that only several branches associated with the polyphase filter circuit corresponding to output samples immediately after a transition of the digital input signal is required to be calculated, thereby reducing the need to store a large number of filter coefficients and eliminating complex computations.
Inventors:
DING LEI (US)
MELANSON JOHN L (US)
FEI XIAOFAN (US)
DUEWER BRUCE (US)
MELANSON JOHN L (US)
FEI XIAOFAN (US)
DUEWER BRUCE (US)
Application Number:
PCT/US2007/013608
Publication Date:
June 05, 2008
Filing Date:
June 08, 2007
Export Citation:
Assignee:
CIRRUS LOGIC INC
International Classes:
H03H17/06
Download PDF: