公开(公告)号：US20190251947A1

公开(公告)日：2019-08-15

申请号：US16394488

申请日：2019-04-25

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Richard Clemow

IPC: G10K11/178 ,  H04R1/10 ,  H04R3/02 ,  G10K11/16

CPC classification number: G10K11/178 ,  G10K11/16 ,  G10K2210/1081 ,  G10K2210/3051 ,  G10K2210/3217 ,  H04R1/1083 ,  H04R3/02

Abstract: A digital circuit arrangement for an ambient noise-reduction system affording a higher degree of noise reduction than has hitherto been possible. The arrangement converts the analog signals into N-bit digital signals at sample rate f0, and then subjects the converted signals to digital filtering. The value of N in some embodiments is 1 but, in any event, is no greater than 8, and f0 may be 64 times the Nyquist sampling rate but, in any event, is substantially greater than the Nyquist sampling rate. This permits digital processing to be used without incurring group delay problems that rule out the use of conventional digital processing in this context. Furthermore, adjustment of the group delay can readily be achieved, in units of a fraction of a micro-second, providing the ability to fine tune the group delay for feed forward applications.

公开(公告)号：US20180247634A1

公开(公告)日：2018-08-30

申请号：US15958028

申请日：2018-04-20

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Anthony J. Magrath ,  Richard Clemow

IPC: G10K11/178

CPC classification number: G10K11/178 ,  G10K2210/1081 ,  G10K2210/3026 ,  G10K2210/3027 ,  G10K2210/3028 ,  G10K2210/3051 ,  H04R3/002

Abstract: A noise cancellation system, comprising: an input for a digital signal, the digital signal having a first sample rate; a digital filter, connected to the input to receive the digital signal; a decimator, connected to the input to receive the digital signal and to generate a decimated signal at a second sample rate lower than the first sample rate; and a processor. The processor comprises: an emulation of the digital filter, connected to receive the decimated signal and to generate an emulated filter output; and a control circuit, for generating a control signal on the basis of the emulated filter output. The control signal is applied to the digital filter to control a filter characteristic thereof.