US 12,255,659 B2
Biasing circuit for setting bias voltages of current source circuit and current sink circuit in charge pump of phase-locked loop circuit by using current digital-to-analog converter and low-pass filter
Heng-Chih Lin, Hsinchu (TW); and Shu-Yu Lin, New Taipei (TW)
Assigned to Airoha Technology Corp., Hsinchu (TW)
Filed by Airoha Technology Corp., Hsinchu (TW)
Filed on May 24, 2022, as Appl. No. 17/751,675.
Prior Publication US 2023/0387919 A1, Nov. 30, 2023
Int. Cl. H03L 7/089 (2006.01); H03L 7/091 (2006.01)
CPC H03L 7/0898 (2013.01) [H03L 7/091 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A biasing circuit for setting a bias voltage of a current source circuit, comprising:
a current digital-to-analog converter, arranged to provide a reference current in response to a current value setting, wherein a first voltage is established due to the reference current; and
a low-pass filter, arranged to apply low-pass filtering to the first voltage to generate a filter output as a second voltage, wherein the bias voltage of the current source circuit is controlled by the second voltage.