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
AssigneeAiroha Technology Corp.
InventorsHeng-Chih Lin, Shu-Yu Lin
Life of this patent
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Abstract
A charge pump of a phase-locked loop (PLL) circuit includes a current source circuit, a current sink circuit, and a biasing circuit. The biasing circuit includes a current digital-to-analog converter (IDAC) and a low-pass filter (LPF). The IDAC provides a reference current in response to a current value setting, wherein a first voltage is established due to the reference current. The LPF applies low-pass filtering to the first voltage to generate a filter output as a second voltage, wherein bias voltages of the current source circuit and the current sink circuit are controlled by the second voltage.
Claims21
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.
A biasing circuit for setting a bias voltage of a current sink 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 sink circuit is controlled by the second voltage.
A charge pump of a phase-locked loop (PLL) circuit, comprising:
- a current source circuit, arranged to provide a source current for charging an output node of the charge pump, wherein the source current is controlled by a first bias voltage applied to the current source circuit;
- a current sink circuit, arranged to provide a sink current for discharging the output node of the charge pump, wherein the sink current is controlled by a second bias voltage applied to the current sink circuit;
- and
- a biasing circuit, arranged to set the first bias voltage and the second bias voltage, wherein the biasing circuit comprises:
- 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 first bias voltage and the second bias voltage are both controlled by the second voltage.
Dependencies are inferred from the claim text.