Circuit arrangement for converting digital sound-signal values into an analog sound signal
First Claim
1. Circuit arrangement for converting digital sound-signal values into an analog sound signal which has the following features:
- an interpolation filter in which the incoming signal values are converted into a sequence of interpolated signal values of an increased repetition rate,a reduction circuit which reduces the word length of said interpolated signal values and includes a quantizer, an error filter, and an adding stage,a digital-to-analog converter including a plurality of switching stages whose output currents are added at the output end of said digital-to-analog converter,a control circuit which, in response to digital signal values at the output of said quantizer, controls said switching stages in such a way that the sum of the output currents is equal to said applied signal values, and selects respective ones of said switching stages by cyclic step-by-step switching, anda low-pass filter following said digital-to-analog converter which delivers the analog signal.
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Accused Products
Abstract
This circuit arrangement includes an interpolation filter (3) which converts the incoming signal values (A) into interpolated signal values (B) of increased repetition frequency. The interpolated signal values (B) are reduced in word length by means of a quantizer (4a) and by quantization error feedback through an error filter (25). A D/A converter (6) consists of two or more nonweighted switching stages connected in parallel. The activated switching stages deliver currents which are added together at the output end. The D/A converter (6) is controlled by a control circuit (5) which processes the output signals (D) of the quantizer (4a). The activated switching stages are continuously interchanged on a cyclic basis, so that relative resistance tolerances in the circuit average out.
11 Citations
12 Claims
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1. Circuit arrangement for converting digital sound-signal values into an analog sound signal which has the following features:
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an interpolation filter in which the incoming signal values are converted into a sequence of interpolated signal values of an increased repetition rate, a reduction circuit which reduces the word length of said interpolated signal values and includes a quantizer, an error filter, and an adding stage, a digital-to-analog converter including a plurality of switching stages whose output currents are added at the output end of said digital-to-analog converter, a control circuit which, in response to digital signal values at the output of said quantizer, controls said switching stages in such a way that the sum of the output currents is equal to said applied signal values, and selects respective ones of said switching stages by cyclic step-by-step switching, and a low-pass filter following said digital-to-analog converter which delivers the analog signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification