Finite Impulse Response Filter For Producing Outputs Having Different Phases

摘要

A method and system for designing and implementing a finite impulse response (FIR) filter to create a plurality of output signals, each output signal having the same frequency but at a different phase shift from the other output(s), is described. Values are determined for the resistors, or other elements having impedance values, in a FIR filter having a plurality of outputs, such that each output has the same frequency response but a different phase than the other output(s). This is accomplished by the inclusion of a phase factor in the time domain calculation of the resistor values that does not change the response in the frequency domain. The phase shift is constant and independent of the frequency of the output signal.

主权项

1. A method of designing a finite impulse response filter having a delay line containing a plurality of delay elements, comprising:
selecting a desired frequency response for the filter; selecting a plurality of sets of elements having impedances, one element from each set to be coupled to the delay line after each delay element, the values of the elements selected to determine their impedances so that for each set of elements the sum of the outputs of the elements is a signal of the same frequency response as, but a different phase from, the sum of the outputs of another set of elements; and for each set of elements, providing an output connected to all of the elements in the set that is separate from the outputs connected to the other sets of elements.