EP0168220A2
Expired / Lapsed
EP
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Method and apparatus for converting an analog signal to a digital signal using an oversampling technique
Assignee: NEC Corp
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Filing: 1985-07-05
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Granted: —
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Expires: 2005-07-05
Abstract
Abstract An analogue signal on terminal (1) is sampled by a sampler (11) operating at a rate in excess of Nyquist rate. A locally decoded signal is subtracted in a subtracter (12) to produce an error signal which may be integrated (13).and again have the locally decoded signal subtracted (14) to provide a difference signal to a two-level quantizer (15). The output of the quantizer is integrated by an integrator (16) to provide the locally decoded signal. A Nyquist rate digital signal is provided not from the output of the integrator (16) but byway of another integrator (23) preceded by a sampling frequency converter (22) which converts the output of the quantizer (15) down to aR intermediate frequency for digital filtering (20) and re-sampling (21) at Nyquist rate.
Inventors
- 👤 Rikio Maruta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 08:42
CPC Classifications
H; H03; H03M; H03M3/00; H03M3/30; H03M3/458; H03M3/462; H03M3/39; H03M3/412; H03M3/422; H03M3/43; H03M3/436; H03M3/456
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
94 words
An oversampled analog-to-digital conversion method comprising the steps of oversampling an input analog signal at a first frequency higher than the Nyquist frequency to produce a sampled signal; subtracting a local decoded signal from the sampled signal; quantizing the difference signal into a quantized binary signal; and generating the local decoded signal by integration of the quantized binary signal; characterised by converting the quantizied binary signal having a first frequency into a J frequency-reduced signal having a second frequency; and integrating the frequency-reduced signal at the second frequency to provide a converted digital signal.
Claim 2
Dependent Claim
94 words
An oversampled analog-to-digital conversion method comprising the steps of oversampling an input analog signal at a first frequency higher than the Nyquist frequency to produce a sampled signal; subtracting a local decoded signal from the sampled signal; quantizing the difference signal into a quantized binary signal; and generating the local decoded signal by integration of the quantized binary signal; characterised by converting the quantizied binary signal having a first frequency into a J frequency-reduced signal having a second frequency; and integrating the frequency-reduced signal at the second frequency to provide a converted digital signal.
Claim 3
Dependent Claim
109 words
An oversampled analog-to-digital converter comprising means (11) for sampling an input analog signal at a first frequency higher than the Nyquist frequency to produce a sampled signal; a subtracter (12) for subtracting a local decoded signal from the sampled signal; a quantizer (15) for quantizing the output of the subtracter to produce a quantized binary signal; and means (16) for integrating the quantized binary signal to generate the local decoded signal; characterised by converting means (22) for converting the quantized binary signal having a first frequency into a frequency-reduced signal having a second frequency; and an integrator (23) for integrating the frequency-reduced signal to provide a converted digital signal.
Claim 4
Dependent Claim
109 words
An oversampled analog-to-digital converter comprising means (11) for sampling an input analog signal at a first frequency higher than the Nyquist frequency to produce a sampled signal; a subtracter (12) for subtracting a local decoded signal from the sampled signal; a quantizer (15) for quantizing the output of the subtracter to produce a quantized binary signal; and means (16) for integrating the quantized binary signal to generate the local decoded signal; characterised by converting means (22) for converting the quantized binary signal having a first frequency into a frequency-reduced signal having a second frequency; and an integrator (23) for integrating the frequency-reduced signal to provide a converted digital signal.
Claim 5
Dependent Claim
62 words
An oversampled analogue-to-digital converter as claimed in claim 2, characterised in that the converting means (22) includes a plurality of accumulators (224) for performing addition or subtraction in accordance with the quantized binary signal, read only memory means (222) for supplying contents stored therein to the accumulators, and switching means (225) for extracting accumulated outputs from the accumulators and clearing the accumulators.
References Cited (Backward Citations)
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