Patent ID: 7532040
Filing Date: 2009-05-12
Classification: G01R,H03D

Abstract:
1. A frequency coincidence detection circuit comprising: a first counter driven by a first periodic signal for counting one or more frequency edges of said first periodic signal and outputting a first frequency count signal representative of at least a portion of the contents of said first counter; a second counter driven by a second periodic signal for counting one or more frequency edges of said second periodic signal and outputting a second frequency count signal representative of at least a portion of the contents of said second counter; a first frequency sensitivity programmer electrically connected to said first counter and a first programmable sensitivity value input for comparing said first frequency count signal with said sensitivity value input to determine a first coincidence window signal for said first periodic signal; a second frequency sensitivity programmer electrically connected to said second counter and the first sensitivity value input for comparing said second frequency count signal with said sensitivity value input to determine a second coincidence window signal for said second periodic signal; and a coincidence detector electrically connected to said first and second frequency sensitivity programmers for outputting a coincidence pulse when said first and second coincidence window signals correspond.