US 9,813,045 B2
Precision frequency monitor
Qu Gary Jin, Kanata (CA)
Assigned to Microseni Semiconductor ULC, Kanata (CA)
Filed by MICROSEMI SEMICONDUCTOR ULC, Kanata (CA)
Filed on Sep. 9, 2015, as Appl. No. 14/848,403.
Claims priority of provisional application 62/051,368, filed on Sep. 17, 2014.
Prior Publication US 2016/0079961 A1, Mar. 17, 2016
Int. Cl. G01R 23/02 (2006.01); H03H 21/00 (2006.01)
CPC H03H 21/0012 (2013.01) [G01R 23/02 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A precision frequency monitor for providing a precision frequency monitor (PFM) output value indicative of the precision of the frequency or period of an input reference signal, comprising:
an averaging module responsive to an average signal Tx representing an average frequency or period of said input reference signal during successive predetermined time periods defining operational cycles, said averaging module being operative to average said average signal Tx over N operational cycles, where N is an integer, and provide an updated PFM value every N operational cycles;
an infinite impulse response (IIR) filter operative to filter said average signal Tx to generate interim PFM values;
a modulo N counter generating a reset signal every N operational cycles to prompt said averaging module to output said updated PFM value;
said IIR filter including an output switch operative to select said interim PFM values within each sequence of N operational cycles as said PFM output value, and said updated PFM value in response to said reset signal; and
said IIR filter further receiving as a feedback input said PFM output value.