Filter

摘要

Provided is an FIR filter capable of obtaining predetermined characteristics with a small number of input taps, delay circuits, and multipliers and achieving an improved response and low cost. In a low-pass filter, a band-pass filter, and a high-pass filter based on an FIR filter, a basic filter is configured that gives a basic impulse response function and has a filter coefficient determined from the impulse response function. Filters having different frequency characteristics are configured by changing the time scale or frequency scale of the basic filter. These filters having different frequency characteristics are combined in a cascade form or a step form, thereby constructing an FIR filter having a small number of taps.

主权项

1. A filter for providing desired characteristics,
the filter comprising a combination of a plurality of scaled filters, where said scaled filters are formed by scaling at least one basic filter in the time domain or the frequency domain, wherein said at least one basic filter comprises at least one of a basic low-pass filter and a basic high-pass filter, wherein said at least one basic filter has an impulse response function expressed by a finite piecewise polynomial and wherein said at least one basic filter has a filter coefficient which is derived from a sample point of said impulse response function; wherein said combination of the plurality of scaled filters is selected such that a passband width of said combination is larger than or equal to a predetermined range; and wherein the combination of the plurality of scaled filters is configured to form a passband filter and a stopband filter, wherein said formed pastband filter has passband characteristics satisfying predetermined required characteristics and wherein said formed stopband filter has stopband characteristics satisfy predetermined required characteristics.