# US 11,115,046 B2 · Closed loop control in a camera module

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- Number: US 11,115,046 B2
- Document ID: US11115046B2
- Status: Granted
- Kind: B2
- Application number: 16/431,276
- Filed: 2019-06-04
- Published: 2019-12-12
- Granted: 2021-09-07
- Earliest claimed: 2018-06-11
- Assignees: Cirrus Logic, Inc.
- Applicants: Cirrus Logic International Semiconductor Ltd.
- Inventors: Vamsikrishna Parupalli; Mark May; Saurabh Singh; Ramya Balasundaram; Mengde Wang; Eric B. Smith
- Web page: https://patentgrep.com/patent/US11115046B2

## CPC

- H02P 23/0027: {using different modes of control depending on a parameter, e.g. the speed}
- H03M 3/432: {the quantiser being a pulse width modulation type analogue/digital converter, i.e. differential pulse width modulation}
- H02P 7/025: the DC motors being of the moving coil type, e.g. voice coil motors
- H02P 25/034: Voice coil motors (voice coil motors driven by DC H02P7/025)
- H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence)
- H02P 27/08: with pulse width modulation
- H03M 1/122: {Shared using a single converter or a part thereof for multiple channels, e.g. a residue amplifier for multiple stages}
- H03M 1/504: {using pulse width modulation}
- H03M 1/822: {using pulse width modulation}
- H03M 3/392: {Arrangements for selecting among plural operation modes, e.g. for multi-standard operation}
- H04N 23/667: Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
- H04N 23/67: Focus control based on electronic image sensor signals
- H04N 23/695: Control of camera direction for changing a field of view, e.g. pan, tilt or based on tracking of objects
- G03B 3/10: Power-operated focusing
- G03B 5/00: Adjustment of optical system relative to image or object surface other than for focusing
- G03B 2205/0007: Movement of one or more optical elements for control of motion blur
- G03B 2205/0069: using electromagnetic actuators, e.g. voice coils
- H04N 23/687: {by shifting the lens or sensor position}
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)

## Abstract

A system may include an output stage for driving a load at an output of the output stage, a pulse-width modulation mode path configured to pre-drive the output stage in a first mode of operation, a linear mode path configured to pre-drive the output stage in a second mode of operation and a loop filter coupled at its input to the output of the output stage and coupled at its output to both of the pulse-width modulation mode path and the linear mode path. The pulse-width modulation mode path and the linear mode path may be configured such that a first transfer function between the output of the loop filter and the output of the output stage is substantially equivalent to a second transfer function between the output of the loop filter and the output of the output stage.

## Claims

### Claim 1

A system comprising:
an output stage for driving a load at an output of the output stage;
a pulse-width modulation mode path configured to pre-drive the output stage in a first mode of operation;
a linear mode path configured to pre-drive the output stage in a second mode of operation; and
a loop filter, wherein an input of the loop filter is coupled to the output of the output stage and wherein an output of the loop filter is coupled to both of the pulse-width modulation mode path and the linear mode path;
wherein the pulse-width modulation mode path and the linear mode path are configured such that a first transfer function between the output of the loop filter and the output of the output stage through the pulse-width modulation mode path is substantially equivalent to a second transfer function between the output of the bop filter and the output of the output stage through the linear mode path,
such that an output of the loop filter after switching between the first mode of operation and the second mode of operation settles to approximately the same value as the output of the loop filter before switching between the first mode of operation and the second mode of operation.

### Claim 2 (depends on 1)

The system of claim 1, wherein the pulse-width modulation mode path comprises a pulse-width modulation quantizer and a pulse-width modulation pre-driver to the output stage.

### Claim 3 (depends on 1)

The system of claim 1, wherein the linear mode path comprises a linear pre-driver to the output stage.

### Claim 4 (depends on 1)

The system of claim 1, wherein the output stage comprises a voltage driver in both the first mode of operation and the second mode of operation.

### Claim 5 (depends on 1)

The system of claim 1, wherein:
the loop filter is configured to output a proportional voltage required to generate a desired output current at the output of the output stage;
in the first mode of operation, the proportional voltage is quantized and buffered by the pulse-width mode modulation path and the output stage to generate the desired output current; and
in the second mode of operation, the proportional voltage is buffered by the linear mode path and the output stage to generate the desired output current.

### Claim 6 (depends on 5)

The system of claim 5, wherein in the first mode of operation, the proportional voltage is quantized, buffered, and amplified by the pulse-width mode modulation path and the output stage to generate the desired output current.

### Claim 7 (depends on 5)

The system of claim 5, wherein in the second mode of operation, the proportional voltage is buffered and amplified by the linear mode path and the output stage to generate the desired output current.

### Claim 8 (depends on 1)

The system of claim 1, wherein the load comprises a motor within a camera module for controlling a position associated with a camera of the camera module.

### Claim 9 (depends on 8)

The system of claim 8, wherein an input of the loop filter is indicative of a current for driving the motor.

### Claim 10

A method comprising:
in a first mode of operation, pre-driving with a pulse-width modulation mode path an output stage for driving a load at an output of the output stage;
in a second mode of operation, pre-driving the output stage with a linear mode path; and
filtering an output signal with a loop filter, wherein an input of the loop filter is coupled to the output of the output stage and wherein an output of the loop filter is coupled to both of the pulse-width modulation mode path and the linear mode path;
wherein the pulse-width modulation mode path and the linear mode path are configured such that a first transfer function between the output of the loop filter and the output of the output stage through the pulse-width modulation mode path is substantially equivalent to a second transfer function between the output of the loop filter and the output of the output stage through the linear mode path,
such that an output of the loop filter after switching between the first mode of operation and the second mode of operation settles to approximately the same value as the output of the loop filter before switching between the first mode of operation and the second mode of operation.

### Claim 11 (depends on 10)

The method of claim 10, wherein the pulse-width modulation mode path comprises a pulse-width modulation quantizer and a pulse-width modulation pre-driver to the output stage.

### Claim 12 (depends on 10)

The method of claim 10, wherein the linear mode path comprises a linear pre-driver to the output stage.

### Claim 13 (depends on 10)

The method of claim 10, wherein the output stage comprises a voltage driver in both the first mode of operation and the second mode of operation.

### Claim 14 (depends on 10)

The method of claim 10, further comprising:
outputting by the loop filter a proportional voltage required to generate a desired output current at the output of the output stage;
in the first mode of operation, quantizing and buffering the proportional voltage by the pulse-width mode modulation path and the output stage to generate the desired output current; and
in the second mode of operation, buffering the proportional voltage by the linear mode path and the output stage to generate the desired output current.

### Claim 15 (depends on 14)

The method of claim 14, further comprising in the first mode of operation, amplifying the proportional voltage by the pulse-width mode modulation path and the output stage to generate the desired output current.

### Claim 16 (depends on 14)

The method of claim 14, further comprising in the second mode of operation, amplifying the proportional voltage by the linear mode path and the output stage to generate the desired output current.

### Claim 17 (depends on 10)

The method of claim 10, wherein the load comprises a motor within a camera module for controlling a position associated with a camera of the camera module.

### Claim 18 (depends on 17)

The method of claim 17, wherein an input of the loop filter is indicative of a current for driving the motor.

### Claim 19 (depends on 10)

The method of claim 10, wherein a feedback path, from the output of the output stage to the input of the loop filter, comprises a current monitor and a combiner, and wherein a transfer function of the feedback path is approximately the same when operating in the first mode of operation and when operating in the second mode of operation.

### Claim 20 (depends on 1)

The system of claim 1, comprising a feedback path from the output of the output stage to the input of the loop filter, wherein the feedback path comprises a current monitor and a combiner, and wherein a transfer function of the feedback path is approximately the same when operating in the first mode of operation and when operating in the second mode of operation.