Using multi-level pulse width modulated signal for real time noise cancellation
US8217820B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 4, 2010 |
| Grant date | Jul 10, 2012 |
| Priority date | — |
| Expiry date | Jan 29, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10K11/17885
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A mixed signal processing circuit includes an analog to PWM converting circuit and a finite impulse response (FIR) filter having a multiple output tapped delay line and a summing and integration circuit. The mixed signal processing circuit converts an input analog signal to a PWM signal, forms a multi-level PWM signal from the PWM signal and one or more delayed versions of the PWM signal, and converts the multi-level PWM signal to an output analog signal. The analog to PWM converting circuit is implemented using a triangle waveform generator and a comparator. The FIR filter is implement using a resistive network to apply scaling coefficients of the FIR filter. The mixed signal processing circuit can be implemented within a noise cancellation headphone to generate a noise cancelling signal or generally in applications that would be benefitted from the combination of analog input/output and digital filter techniques.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.