US 2017/0303032 A1 · OVER-SAMPLING DIGITAL PROCESSING PATH THAT EMULATES NYQUIST RATE (NON-OVERSAMPLING) AUDIO CONVERSION

Abstract

The behavior of a NOS DAC and an analog filter may be emulated by electronic components of an integrated circuit (IC) by upsampling data and applying a digital filter to the upsampled data. For example, the IC may include a zero-order-hold circuit that upsamples data from a first input sample rate to a second, higher input rate. The upsampled data may be passed to an Asynchronous Sample Rate Converter (ASRC) that performs further upsampling (e.g., from 8*Fs-64*Fs). The upsampled data may be passed to a digital low pass filter. The digital low pass filter may emulate, for example, a response of a fifth order Butterworth analog filter to mimic the effect of analog processing. The IC may integrate the upsampling circuit, the low pass digital filter, a digital-to-analog converter (DAC) and an amplifier to provide an audio solution for playing high-fidelity music in a mobile device.

Claims29

Dependent claims

A method, comprising:

receiving an input signal at a first frequency;
upsampling the input signal to achieve a plurality of samples at a second frequency higher than the first frequency that correspond to the input signal;
and
filtering, with a digital low pass filter that models an analog low pass filter, the upsampled plurality of samples, wherein the filtering implements a filter corner that is higher than a Nyquist frequency of the input signal.

1 more element

Dependencies are inferred from the claim text.

Facts

Application

15/099,293Filed 14 Apr 2016

Published

19 Oct 2017

Term ends

Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04R 1/22
Arrangements for obtaining desired frequency or directional characteristics: for obtaining desired frequency characteristic only
H03H 17/0657
The ratio being integer: where the output-delivery frequency is higher than the input sampling frequency, i.e. interpolation
H04R 2430/03
Signal processing covered by H04R, not provided for in its groups: synergistic effects of band splitting and sub-band processing
H04R
Loudspeakers, microphones, gramophone pick-ups or like acoustic electromechanical transducers

Over-sampling digital processing path that emulates nyquist rate (non-oversampling) audio conversion

Life of this patent

Over-sampling digital processing path that emulates nyquist rate (non-oversampling) audio conversion

Life of this patent

Abstract

Claims29