US 12,445,138 B1
Frequency synthesizers having low phase noise
Oleksandr Chenakin, Morgan Hill, CA (US)
Assigned to Anritsu Company, Morgan Hill, CA (US)
Filed by Anritsu Company, Morgan Hill, CA (US)
Filed on Oct. 4, 2023, as Appl. No. 18/376,656.
Application 18/376,656 is a division of application No. 17/582,320, filed on Jan. 24, 2022, granted, now 11,817,871.
Claims priority of provisional application 63/206,163, filed on Feb. 1, 2021.
Claims priority of provisional application 63/142,924, filed on Jan. 28, 2021.
Int. Cl. H03L 7/185 (2006.01); H03B 5/18 (2006.01); H03L 7/087 (2006.01); H03L 7/099 (2006.01)
CPC H03L 7/185 (2013.01) [H03B 5/18 (2013.01); H03L 7/087 (2013.01); H03L 7/099 (2013.01); H03L 2207/10 (2013.01); H03L 2207/12 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A frequency synthesizer comprising:
a phase detector having a first input, a second input, and an output,
a voltage-controlled oscillator having an input coupled to the output of the phase detector and an output;
a feedforward path having an input to receive a reference signal and an output coupled to the first input of the phase detector, the feedforward path comprising:
a first element having an input coupled the input of the feedforward path and further coupled to a first input of a first mixer and an input of a first divider, and an output coupled to an output of the first mixer, where an output of the first divider is coupled to a second input of the first mixer; and
a second element having an input coupled the output of the first element and further coupled to a first input of a second mixer and an input of a second divider, and an output coupled to an output of the second mixer and the output of the feedforward path, where an output of the second divider is coupled to a second input of the second mixer; and
a feedback path having an input coupled to the output of the voltage-controlled oscillator and an output coupled to the second input of the phase detector, the feedback path comprising:
a third element having an input coupled the input of the feedback path and further coupled to a first input of a third mixer and an input of a third divider, and an output coupled to an output of the third mixer, where an output of the third divider is coupled to a second input of the third mixer; and
a fourth element having an input coupled the output of the third element and further coupled to a first input of a fourth mixer and an input of a fourth divider, and an output coupled to an output of the fourth mixer and the output of the feedback path, where an output of the fourth divider is coupled to a second input of the fourth mixer.