# US 10,504,471 B2 · Half-power buffer and/or amplifier

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- Number: US 10,504,471 B2
- Document ID: US10504471B2
- Status: Granted
- Kind: B2
- Application number: 15/918,919
- Filed: 2018-03-12
- Published: 2019-03-14
- Granted: 2019-12-10
- Earliest claimed: 2017-09-13
- Assignees: DB HiTek Co., Ltd.
- Applicants: DB HiTek Co., Ltd.
- Inventors: Mun Gyu Kim; Seung Jin Yeo; Dong Gwi Choi; Kyoung Tae Kim
- Web page: https://patentgrep.com/patent/US10504471B2

## CPC

- G09G 3/3614: {Control of polarity reversal in general}
- G09G 3/3677: {suitable for active matrices only}
- G09G 3/3685: {Details of drivers for data electrodes}
- H03F 1/0211: {with control of the supply voltage or current}
- H03F 3/45179: {using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence)}
- H03F 3/45224: {Complementary Pl types having parallel inputs and being supplied in parallel}
- G09G 2310/027: Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
- G09G 2310/0289: Details of voltage level shifters arranged for use in a driving circuit
- G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2330/021: Power management, e.g. power saving
- H03F 2200/417: A switch coupled in the output circuit of an amplifier being controlled by a circuit
- H03F 2200/421: Multiple switches coupled in the output circuit of an amplifier are controlled by a circuit
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H03F: AMPLIFIERS

## Abstract

A half-power buffer and/or amplifier is disclosed. The half-power buffer and/or amplifier includes an amplifying unit including first and second transistors connected between a first voltage source having a first voltage and a third voltage source having a third voltage, and a first output node configured to connect the first and second transistors and to output a voltage over a first voltage range between the first and third voltages, a second output buffer unit including third and fourth transistors connected between a second voltage source having a second voltage and the third voltage source, and a second output node configured to connect the third and fourth transistors and to output a voltage over a second voltage range between the second and third voltages, and a first charge share switch unit connected between the gate of the second transistor and the first voltage source, and configured to perform a charge share and/or equalization operation.

## Claims

### Claim 1

A half-power buffer and/or amplifier comprising:
an amplifying unit configured to amplify a differential input signal, the amplifying unit comprising first to fourth nodes configured to output first to fourth amplified outputs;
a first output buffer unit comprising (i) first and second transistors connected between a first voltage source having a first voltage and a third voltage source having a third voltage, and (ii) a first output node configured to connect the first and second transistors, the first and second transistors having gates connected to corresponding ones of the first and second nodes, respectively, the first output node being configured to output a voltage over a first voltage range between the first voltage and the third voltage;
a second output buffer unit comprising (i) third and fourth transistors connected between a second voltage source having a second voltage and the third voltage source, and (ii) a second output node configured to connect the third and fourth transistors, the third and fourth transistors having gates connected to corresponding ones of the third and fourth nodes, respectively, the second output node being configured to output a voltage over a second voltage range between the second voltage and the third voltage;
a third output node configured to connect the first output node of the first output buffer unit and the second output node of the second output buffer unit;
a first charge share switch unit connected between the gate of the second transistor and the first voltage source, and configured to control the second transistor and/or equilibrate a voltage at the first output node with the third voltage in response to a first control signal; and
a first output switch unit comprising a seventh switch (i) connected between the first node and the gate of the first transistor and (ii) configured to receive a third control signal, an eighth switch (iii) connected between the second voltage source and the gate of the second transistor and (iv) configured to receive a fourth control signal, and a ninth switch (v) connected between the first voltage source and the gate of the first transistor and (vi) configured to receive a fifth control signal, wherein:
the first charge share switch unit comprises first and second switches connected between the first voltage source and the gate of the second transistor,
the first and second switches provide the first voltage to the gate of the second transistor in response to the first control signal, and
the eighth switch provides the second voltage to the gate of the second transistor in response to the fourth control signal.

### Claim 2 (depends on 1)

The half-power buffer and/or amplifier according to claim 1, further comprising:
a second charge share switch unit connected between the gate of the third transistor and the second voltage source, and configured to control the third transistor and/or equilibrate a voltage at the second output node with the third voltage in response to a second control signal, wherein:
the second charge share switch unit comprises fourth and fifth switches connected between the second voltage source and the gate of the third transistor, and
the fourth and fifth switches provide the second voltage of the second voltage source to the gate of the third transistor in response to the second control signal.

### Claim 3 (depends on 1)

The half-power buffer and/or amplifier according to claim 1, wherein the first voltage is higher than the third voltage, and the second voltage is lower than the third voltage.

### Claim 4 (depends on 2)

The half-power buffer and/or amplifier according to claim 2, wherein:
the first switch is configured to receive a first polarity control signal, and the second switch is configured to receive a first charge share signal.

### Claim 5 (depends on 4)

The half-power buffer and/or amplifier according to claim 4, wherein the first charge share switch unit further comprises a third switch connected between the second node and the gate of the second transistor, configured to float or electrically disconnect the first output buffer unit from the second node in response to the third control signal.

### Claim 6 (depends on 4)

The half-power buffer and/or amplifier according to claim 4, further comprising:
a first reset switch unit connected between the gate of the second transistor and the third voltage source, configured to reset the first output node of the first output buffer unit to the third voltage in response to a first reset control signal, wherein the first reset switch unit provides the third voltage to the gate of the second transistor in response to the first reset control signal.

### Claim 7 (depends on 6)

The half-power buffer and/or amplifier according to claim 6, wherein the first reset switch unit resets the first output node of the first output buffer unit to the third voltage when equilibrating the second output node with the third voltage.

### Claim 8 (depends on 5)

The half-power buffer and/or amplifier according to claim 5, wherein:
the fourth switch is configured to receive the first polarity control signal, and the fifth switch is configured to receive a second charge share signal.

### Claim 9 (depends on 8)

The half-power buffer and/or amplifier according to claim 8, wherein the second charge share switch unit further comprises a sixth switch connected to the third node and the gate of the third transistor, and is configured to float or electrically disconnect the second output buffer unit from the third node in response to the fourth control signal.

### Claim 10 (depends on 6)

The half-power buffer and/or amplifier according to claim 6, further comprising:
a second reset switch unit connected between the gate of the third transistor and the third voltage source, configured to reset the second output node of the second output buffer unit to the third voltage in response to a second reset control signal, wherein the second reset switch unit provides the third voltage to the gate of the third transistor in response to the second reset control signal.

### Claim 11 (depends on 10)

The half-power buffer and/or amplifier according to claim 10, wherein the second reset switch unit resets the second output node of the second output buffer unit to the third voltage when equilibrating the first output node with the third voltage.

### Claim 12 (depends on 1)

The half-power buffer and/or amplifier according to claim 1, further comprising: a second output switch unit comprising (i) a tenth switch connected between the fourth node and the gate of the fourth transistor and (ii) configured to receive the fourth control signal, an eleventh switch (iii) connected between the first voltage source and the gate of the third transistor and (iv) configured to receive the third control signal, and a twelfth switch (v) connected between the second voltage source and the gate of the fourth transistor and (vi) configured to receive a sixth control signal, wherein the eleventh switch provides the first voltage of the first voltage source to the gate of the third transistor in response to the third control signal.

### Claim 13 (depends on 12)

The half-power buffer and/or amplifier according to claim 12, wherein:
the first reset switch unit comprises thirteenth and fourteenth switches connected between the gate of the second transistor and the third voltage source; and
the thirteenth switch is configured to receive the fifth control signal, and the fourteenth switch is configured to receive a second polarity control signal.

### Claim 14 (depends on 13)

The half-power buffer and/or amplifier according to claim 13, further comprising:
a fifteenth switch (i) connected between the gate of the third transistor and the third voltage source and (ii) configured to receive the sixth control signal; and
a sixteenth switch (i) connected between the gate of the third transistor and the third voltage source and (ii) configured to receive the second polarity control signal.

### Claim 15 (depends on 13)

The half-power buffer and/or amplifier according to claim 13, wherein the second polarity control signal is an inverted first polarity control signal.

### Claim 16

A half-power buffer and/or amplifier comprising:
an amplifying unit configured to amplify a differential input signal, the amplifying unit comprising first to fourth nodes configured to output first to fourth outputs;
a first output buffer unit comprising first and second transistors connected between a first voltage source having a first voltage and a third voltage source having a third voltage, and a first output node configured to connect the first and second transistors, the first transistor having a gate connected to the first node, the second transistor having a gate connected to the second node;
a second output buffer unit comprising third and fourth transistors connected between a second voltage source having a second voltage and the third voltage source, and a second output node configured to connect the third and fourth transistors, the third and fourth transistors having gates connected to corresponding ones of the third and fourth nodes, respectively, the second output node being configured to output a voltage over a second voltage range between the second voltage and the third voltage;
a first charge share switch unit connected between the gate of the second transistor and the first voltage source;
a first output switch unit comprising a seventh switch (i) connected between the first node and the gate of the first transistor and (ii) configured to receive a third control signal, an eighth switch (iii) connected between the second voltage source and the gate of the second transistor and (iv) configured to receive a fourth control signal, and a ninth switch (v) connected between the first voltage source and the gate of the first transistor and (vi) configured to receive a fifth control signal;
a second charge share switch unit connected between the gate of the third transistor and the second voltage source;
a second output switch unit comprising (i) a tenth switch connected between the fourth node and the gate of the fourth transistor and (ii) configured to receive the fourth control signal, an eleventh switch (iii) connected between the first voltage source and the gate of the third transistor and (iv) configured to receive the third control signal, and a twelfth switch (v) connected between the second voltage source and the gate of the fourth transistor and (vi) configured to receive a sixth control signal; and
a third output node configured to connect the first and second output nodes,
wherein:
the first output buffer unit outputs a first output voltage over a first voltage range between the first voltage and the third voltage on the third output node in a first operation period;
the second output buffer unit outputs a voltage over a second voltage range between the second voltage and the third voltage on the third output node in a second operation period;
the first and second charge share switch units control the second and third transistors and/or equilibrate a voltage at the third output node with the third voltage in a third operation period between the first operation period and the second operation period,
the first charge share switch unit comprises first and second switches connected between the first voltage source and the gate of the second transistor and a third switch connected between the second node and the gate of the second transistor,
the second charge share switch unit comprises fourth and fifth switches connected between the second voltage source and the gate of the third transistor,
the first and second switches provide the first voltage of the first voltage source to the gate of the second transistor in response to the first control signal,
the fourth and fifth switches provide the second voltage of the second voltage source to the gate of the third transistor in response to the first control signal,
the eighth switch provides the second voltage of the second voltage source to the gate of the second transistor in response to the fourth control signal, and
the eleventh switch provides the first voltage of the first voltage source to the gate of the third transistor in response to the third control signal.

### Claim 17 (depends on 16)

The half-power buffer and/or amplifier according to claim 16, wherein the charge share switch unit comprises:
a first charge share switch connected between the gate of the second transistor and the first voltage source, configured to control the second transistor and/or equilibrate a voltage at the first output node with the third voltage in response to the first control signal; and
a second charge share switch connected between the gate of the third transistor and the second voltage source, configured to control the third transistor and/or equilibrate a voltage at the second output node with the third voltage in response to a second control signal.

### Claim 18 (depends on 1)

A source driver comprising;
a latch unit configured to store data;
a level shifter unit configured to convert a voltage level of data from the latch unit;
a digital-to-analog converter unit configured to convert an output from the level shifter unit into an analog signal; and
an output buffer configured to amplify the analog signal and to output the amplified analog signal,
wherein the output buffer comprises the half-power buffer and/or amplifier defined in claim 1.