US 9,810,726 B2
Method and system for calibrating phases of comb teeth in comb signal with pilot tone and using calibrated comb teeth phases to measure a device under test
Troels Studsgaard Nielsen, Aalborg (DK); and Felice Francesco Tafuri, Aalborg (DK)
Assigned to Keysight Technologies, Inc., Santa Rosa, CA (US)
Filed by Keysight Technologies, Inc., Minneapolis, MN (US)
Filed on Sep. 9, 2015, as Appl. No. 14/848,971.
Prior Publication US 2017/0067949 A1, Mar. 9, 2017
Int. Cl. G01R 35/00 (2006.01); G01R 25/00 (2006.01); H03L 7/20 (2006.01)
CPC G01R 25/00 (2013.01) [G01R 35/007 (2013.01); H03L 7/20 (2013.01)] 20 Claims
OG exemplary drawing
 
19. A method, comprising:
receiving at an input of a measurement system a comb signal having a plurality of comb teeth, wherein selected comb teeth among the plurality of comb teeth span a selected bandwidth of the comb signal;
the measurement system sequentially measuring calibration phases of the selected comb teeth using a local oscillator (LO) signal output by a programmable frequency generator, the LO signal having a frequency and phase which are changed for each sequential measurement; and
adjusting the measured calibration phases of the selected comb teeth to account for the change of phase in the LO signal from measurement of one selected comb tooth to measurement of a next selected comb tooth to ascertain reference phase differences between the selected comb teeth,
wherein adjusting the measured calibration phases of the selected comb teeth to account for the change of phase in the LO signal from measurement of the one selected comb tooth to measurement of the next selected comb tooth includes the measurement system measuring a first phase and a second phase of a pilot tone using the LO signal output by the programmable frequency generator, respectively, before and after the frequency and phase of the LO signal changes from measurement of the one comb tooth to measurement of the next comb tooth, and applying to the measured calibration phases of the selected comb teeth the measured first and second phases of the pilot tone, and
wherein the frequency of the pilot tone is maintained to be substantially the same in measuring the first phase of the pilot tone as in measuring the second phase of the pilot tone.