# US 9,436,023 B2 · Operational amplifier

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- Number: US 9,436,023 B2
- Document ID: US9436023B2
- Status: Granted
- Kind: B2
- Application number: 14/549,553
- Filed: 2014-11-21
- Published: 2015-11-19
- Granted: 2016-09-06
- Earliest claimed: 2014-05-15
- Assignees: Novatek Microelectronics Corp.
- Applicants: NOVATEK Microelectronics Corp.
- Inventors: Wei-Ta Chiu
- Web page: https://patentgrep.com/patent/US9436023B2

## CPC

- G02F 1/133: Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements (arrangements or circuits for control of liquid crystal elements in a matrix, not structurally associated with these elements G09G3/36)
- G02F 1/13306: {Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence)}
- G09G 3/3685: {Details of drivers for data electrodes}
- H03F 3/3022: {CMOS common source output SEPP amplifiers (H03F3/3008 takes precedence)}
- H03F 3/45179: {using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence)}
- H03F 3/45183: {Long tailed pairs (H03F3/4521, H03F3/45237 take precedence)}
- G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit
- G09G 2310/0297: Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
- H03F 2200/366: Multiple MOSFETs are coupled in parallel
- H03F 2203/45154: the bias at the input of the amplifying transistors being controlled
- H03F 2203/45702: the LC comprising two resistors
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- 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

An operational amplifier comprises a first metal-oxide-semiconductor field effect transistor (MOSFET), comprising a first drain, a first gate and a first source; a second MOSFET, comprising a second drain, a second gate and a second source, the second source coupled to the first source of the first MOSFET; and a bias source, coupled between a first specific level and the first source of the first MOSFET and the second source of the second MOSFET; wherein the first MOSFET and the second MOSFET are depletion-type.

## Claims

### Claim 1

An operational amplifier, comprising:
a first metal-oxide-semiconductor field effect transistor (MOSFET), comprising a first drain, a first gate and a first source;
a second MOSFET, comprising a second drain, a second gate and a second source, the second source coupled to the first source of the first MOSFET; and
a bias source, coupled between a first specific voltage level and the first source of the first MOSFET and the second source of the second MOSFET;
wherein the first MOSFET and the second MOSFET are depletion-type;
wherein a first body of the first MOSFET and a second body of the second MOSFET are coupled to a second specific voltage level, and the second specific voltage level is equal to the first specific voltage level or between the first specific voltage level and a voltage level of the first source of the first MOSFET and the second source of the second MOSFET;
wherein the first MOSFET and the second MOSFET are N-channel MOSFETs, and the first specific voltage level is a ground voltage level.

### Claim 2 (depends on 1)

The operational amplifier of claim 1 further comprising:
an active load, coupled to the first drain of the first MOSFET and the second drain of the second MOSFET; and
an output stage, coupled to the active load, for generating an output voltage.

### Claim 3 (depends on 1)

The operational amplifier of claim 1, wherein the operational amplifier is utilized in a Liquid Crystal Display (LCD) driver.