System and method of automatic power control system and bias current control circuit

Patent metadata

Field	Value
Publication number	US-2017366189-A1
Application number	US-201615338671-A
Country	US
Kind code	A1
Filing date	Oct 31, 2016
Priority date	Jun 16, 2016
Publication date	Dec 21, 2017
Grant date	—

Abstract

A bias-current-control circuit is provided. The bias-current-control circuit includes a transconductance circuit, a constant-current source, and a current-mirror circuit. The transconductance circuit is connected to a node and detects a voltage signal to generate a first current. The constant-current source is connected to the node and generates a tail current. The current-mirror circuit includes a reference current terminal and a bias current terminal, and the reference current terminal is coupled to the node. A second current which flows through the reference current terminal is determined by a current difference between the tail current and the first current. A bias current which flows through the bias current terminal is generated based on the second current. Furthermore, the second current and the bias current are in a predetermined ratio.

First claim

What is claimed is:

1 . A bias-current-control circuit, comprising:
a transconductance circuit, connecting a node and detecting a voltage signal to generate a first current; a constant-current source, connecting the node and generating a tail current; and a current-mirror circuit, including a reference current terminal and a bias current terminal, and the reference current terminal is coupled to the node; wherein a second current which flows through the reference current terminal is determined by a current difference between the tail current and the first current; wherein a bias current which flows through the bias current terminal is generated based on the second current; wherein the second current and the bias current are in a predetermined ratio.

2 . The bias-current-control circuit as claimed in claim 1 , further comprising:
a second transconductance circuit, provided between the reference current terminal and the node.

3 . The bias-current-control circuit as claimed in claim 2 , further comprising a low-pass filter;
wherein an input terminal of the low-pass filter is connected to a first input terminal of the transconductance circuit, and an output terminal of the low-pass filter is connected to a second input terminal of the second transconductance circuit.

4 . The bias-current-control circuit as claimed in claim 1 , further comprising:
a capacitor, connected to the constant-current source in parallel; wherein a filtered current is generated by filtering the first current through the capacitor; wherein the second current is equal to a second current difference between the tail current and the filtered current.

5 . The bias-current-control circuit as claimed in claim 2 , wherein the transconductance circuit and the second transconductance circuit are metal-oxide-semiconductor field-effect transistors or bipolar junction transistors.

6 . An automatic power-control system, comprising:
an oscillator circuit, outputting a voltage signal; and a bias-current-control circuit, including: a transconductance circuit, connecting a node and detecting the voltage signal to generate a first current; a constant-current source, connecting the node and generating a tail current; and a current-mirror circuit, including a reference current terminal coupled to the node and a bias current terminal connected to a current input terminal of the oscillator circuit; wherein a second current which flows through the reference current terminal is determined by a current difference between the tail current and the first current; wherein a bias current which flows through the bias current terminal is generated based on the second current; wherein the second current and the bias current are in a predetermined ratio.

7 . The automatic power-control system as claimed in claim 6 , wherein the bias-current-control circuit further comprises:
a second transconductance circuit, provided between the reference current terminal and the node.

8 . The automatic power-control system as claimed in claim 7 , wherein the bias-current-control circuit further comprises a low-pass filter;
wherein an input terminal of the low-pass filter is connected to a first input terminal of the transconductance circuit, and an output terminal of the low-pass filter is connected to a second input terminal of the second transconductance circuit.

9 . The automatic power-control system as claimed in claim 6 , wherein the bias-current-control circuit further comprises:
a capacitor, connected to the constant-current source in parallel; wherein a filtered current is generated by filtering the first current through the capacitor; wherein the second current is equal to a second current difference between the tail current and the filtered current.

10 . The automatic power-control system as claimed in claim 7 , wherein the bias-current-control circuit further comprises:
a capacitor, connected to the constant-current source in parallel; wherein a filtered current is generated by filtering the first current through the capacitor; wherein the second current is equal to a second current difference between the tail current and the filtered current.

11 . The automatic power-control system as claimed in claim 8 , wherein the bias-current-control circuit further comprises:
a capacitor, connected to the constant-current source in parallel; wherein a filtered current is generated by filtering the first current through the capacitor; wherein the second current is equal to a second current difference between the tail current and the filtered current.

12 . The automatic power-control system as claimed in claim 7 , wherein the transconductance circuit and the second transconductance circuit are metal-oxide-semiconductor field-effect transistors or bipolar junction transistors.

13 . An automatic power-control method, comprising:
generating, by a transconductance circuit, a first current based on a voltage signal output by an oscillator circuit; generating, by a current-mirror circuit, a bias current according to a current difference between the first current and a tail current of a constant-current source; and providing the bias current to the oscillator circuit; wherein the second current and the bias current are in a predetermined ratio.

Assignees

• Via Alliance Semiconductor Co Ltd

Inventors

• Zhou Yongqi

Classifications

• H03B5/32

  being a piezoelectric resonator (selection of piezoelectric material H10N30/00) · CPC title

• G05F1/56

  using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence) · CPC title

• H03L5/02 Primary

  of power · CPC title

• H03B2200/0062

  Bias and operating point · CPC title

• H03B5/1215 Primary

  the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair · CPC title