# US 10,483,845 B2 · Charge pump having level-shifting mechanism

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- Number: US 10,483,845 B2
- Document ID: US10483845B2
- Status: Granted
- Kind: B2
- Application number: 16/137,534
- Filed: 2018-09-20
- Published: 2019-06-27
- Granted: 2019-11-19
- Earliest claimed: 2017-12-26
- Assignees: Mediatek Inc.
- Applicants: Mediatek Inc.
- Inventors: Yu-Li Hsueh; Chih-Hsien Shen; Chao-Ching Hung; Po-Chun Huang
- Web page: https://patentgrep.com/patent/US10483845B2

## CPC

- H02M 3/07: using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps}
- H03L 7/0895: {Details of the current generators (H03L7/0893 takes precedence)}
- H03L 7/0896: {the current generators being controlled by differential up-down pulses}
- H03L 7/099: concerning mainly the controlled oscillator of the loop
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B)

## Abstract

The present invention provides a charge pump including a pull-up circuit for selectively providing charges to an output terminal of the charge pump, and the pull-up circuit comprises a transistor, a capacitor and a switched-capacitor circuit, wherein the capacitor is coupled to an electrode of the transistor, and the switched-capacitor circuit is coupled between a supply voltage and another electrode of the transistor. The switched-capacitor circuit is configured to boost a voltage of the other electrode of the transistor to charge the capacitor via the transistor, then the capacitor and the output terminal of the charge pump are under a charge distribution operation.

## Claims

### Claim 1

A charge pump, comprising:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to one electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage and another electrode of the first transistor, for boosting a voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor, then the first capacitor and the output terminal of the charge pump are under a charge distribution operation;
wherein when the first capacitor and the output terminal of the charge pump are under the charge distribution operation, the first capacitor is electrically disconnected from the supply voltage.

### Claim 2

A charge pump, comprising:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to one electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage and another electrode of the first transistor, for boosting a voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor, then the first capacitor and the output terminal of the charge pump are under a charge distribution operation;
wherein the first transistor is a P-type transistor, and the switched-capacitor circuit comprises:
a second capacitor, wherein a first node of the second capacitor is coupled to a first clock signal;
a first switch, coupled between the supply voltage and a second node of the second capacitor, wherein the first switch is controlled by a second clock signal to connect or disconnect the supply voltage to the second node of the second capacitor, wherein phases of the second clock signal and the first clock signal are inverted; and
a second switch, coupled between the second node of the second capacitor and a source electrode of the first transistor, wherein the second switch is controlled by the first clock signal to connect or disconnect the second capacitor to the source electrode of the first transistor.

### Claim 3 (depends on 2)

The charge pump of claim 2, further comprising:
a third switch, coupled between a drain electrode of the first transistor and the output terminal of the charge pump, wherein the third switch is controlled by the second clock signal to connect or disconnect the drain electrode of the first transistor to the output terminal of the charge pump.

### Claim 4

A charge pump, comprising:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to one electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage and another electrode of the first transistor, for boosting a voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor, then the first capacitor and the output terminal of the charge pump are under a charge distribution operation;
wherein the pull-up circuit further comprises:
a second transistor, wherein a gate electrode of the second transistor is coupled to a gate electrode of the first transistor, and a first electrode of the second transistor is coupled to the supply voltage; and
a resistor, coupled between a second electrode of the second transistor and a ground voltage, and the second electrode of the second transistor is also coupled to its gate electrode.

### Claim 5 (depends on 4)

The charge pump of claim 4, wherein the first transistor and the second transistor are P-type transistors, and the second transistor is barely off when the switched-capacitor circuit boosts the voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor.

### Claim 6

A charge pump, comprising:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to one electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage and another electrode of the first transistor, for boosting a voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor, then the first capacitor and the output terminal of the charge pump are under a charge distribution operation;
a pull-down circuit, comprising:
a current source, coupled to the output terminal of the charge pump via a switch, for selectively discharging the output terminal of the charge pump;
wherein the pull-down circuit further comprises:
a third capacitor, wherein a first node of the third capacitor is coupled to a first clock signal, and a second node of the third capacitor is coupled to the current source;
wherein the switch is controlled by a second clock signal to connect or disconnect the current source to the output terminal of the charge pump, and the phases of the second clock signal and the first clock signal are inverted.

### Claim 7

A phase-locked loop, comprising:
a phase detector, for receiving an input signal and a feedback signal to generate a detection result;
a charge pump, for generating a control signal according to the detection result, wherein the charge pump comprises:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to one electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage another electrode of the first transistor, for boosting a voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor, then the first capacitor and the output terminal of the charge pump are under a charge distribution operation; wherein when the first capacitor and the output terminal of the charge pump are under the charge distribution operation, the first capacitor is electrically disconnected from the supply voltage; and
a voltage-controlled oscillator, for generating an output clock signal according to the control signal; and
a frequency divider, for frequency-dividing the output clock signal to generate the feedback signal.

### Claim 8 (depends on 7)

The phase-locked loop of claim 7, wherein the first transistor is a P-type transistor, and the switched-capacitor circuit comprises:
a second capacitor, wherein a first node of the second capacitor is coupled to a first clock signal;
a first switch, coupled between the supply voltage and a second node of the second capacitor, wherein the first switch is controlled by a second clock signal to connect or disconnect the supply voltage to the second node of the second capacitor, wherein phases of the second clock signal and the first clock signal are inverted; and
a second switch, coupled between the second node of the second capacitor and a source electrode of the first transistor, wherein the second switch is controlled by the first clock signal to connect or disconnect the second capacitor to the source electrode of the first transistor.

### Claim 9 (depends on 8)

The phase-locked loop of claim 8, further comprising:
a third switch, coupled between a drain electrode of the first transistor and the output terminal of the charge pump, wherein the third switch is controlled by the second clock signal to connect or disconnect the drain electrode of the first transistor to the output terminal of the charge pump.

### Claim 10 (depends on 7)

The phase-locked loop of claim 7, wherein the pull-up circuit further comprises:
a second transistor, wherein a gate electrode of the second transistor is coupled to a gate electrode of the first transistor, and a first electrode of the second transistor is coupled to the supply voltage; and
a resistor, coupled between a second electrode of the second transistor and a ground voltage, and the second electrode of the second transistor is also coupled to its gate electrode.

### Claim 11 (depends on 10)

The phase-locked loop of claim 10, wherein the first transistor and the second transistor are P-type transistors, and the second transistor is barely off when the switched-capacitor circuit boosts the voltage of the other electrode of the first transistor to charge the first capacitor via the first transistor.

### Claim 12 (depends on 7)

The phase-locked loop of claim 7, further comprising:
a pull-down circuit, comprising:
a current source, coupled to the output terminal of the charge pump via a switch, for selectively discharging the output terminal of the charge pump.

### Claim 13 (depends on 12)

The phase-locked loop of claim 12, wherein the pull-down circuit further comprises:
a third capacitor, wherein a first node of the third capacitor is coupled to a first clock signal, and a second node of the third capacitor is coupled to the current source;
wherein the switch is controlled by a second clock signal to connect or disconnect the current source to the output terminal of the charge pump, and the phases of the second clock signal and the first clock signal are inverted.

### Claim 14

A charge pump, comprising:
a pull-up circuit, for selectively providing charges to an output terminal of the charge pump, wherein the pull-up circuit comprises:
a first transistor;
a first capacitor, coupled to a first electrode of the first transistor; and
a switched-capacitor circuit, coupled between a supply voltage and a second electrode of the transistor,
a switch, coupled between the first electrode of the first transistor and the output terminal of the charge pump;
wherein when the pull-up circuit operates in a first phase, the switched-capacitor circuit is controlled to charge the first capacitor via the first transistor, and the switch is controlled to disconnect the first electrode of the first transistor from the output terminal of the charge pump; and when the pull-up circuit operates in a second phase, the switched-capacitor circuit is controlled to be disconnected from the second electrode of the first transistor, and the switch is controlled to connect the first electrode of the first transistor to the output terminal of the charge pump.

### Claim 15 (depends on 14)

The charge pump of claim 14, wherein the switch is a third switch, the first transistor is a P-type transistor, and the switched-capacitor circuit comprises:
a second capacitor, wherein a first node of the second capacitor is coupled to a first clock signal;
a first switch, coupled between the supply voltage and a second node of the second capacitor, wherein the first switch is controlled by a second clock signal to connect or disconnect the supply voltage to the second node of the second capacitor, wherein phases of the second clock signal and the first clock signal are inverted; and
a second switch, coupled between the second node of the second capacitor and a source electrode of the first transistor, wherein the second switch is controlled by the first clock signal to connect or disconnect the second capacitor to the source electrode of the first transistor.

### Claim 16 (depends on 15)

The charge pump of claim 15, wherein the third switch is controlled by the second clock signal to connect or disconnect the drain electrode of the first transistor to the output terminal of the charge pump.