Amplifier, liquid crystal displaying driving circuit and liquid crystal display apparatus

• US 9,520,848 B2
• Filed: 06/26/2012
• Issued: 12/13/2016
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kishikawa, Teisuke
• Primary Examiner(s): AWAD, AMR A
• Assistant Examiner(s): Chow, Wing
• Application Number:
  US13/533,374
• Publication Number:
  US 20130016087A1
• Time in Patent Office: 1,631 Days
• Field of Search: 345/212, 345/87
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: H03F 2203/45466 the CSC being controlled, e.g. by a signal derived from a non specified place in the dif amp circuit
• CPC Class Codes: H03F 2203/45471 the CSC comprising one or more extra current sources
• CPC Class Codes: H03F 3/3022 CMOS common source output SEPP amplifiers H03F3/3008 takes precedence
• CPC Class Codes: H03F 3/45183 Long tailed pairs H03F3/4521, H03F3/45237 take precedence

Abstract

Disclosed herein is an amplifier including a voltage follower circuit having differential input terminals and an output terminal fed back to a first one of the differential input terminals, the voltage follower circuit being configured to amplify an input signal inputted to a second one of the differential input terminals and output the amplified signal from the output terminal; a first current source configured to supply a predetermined current to the voltage follower circuit; and a second current source configured to supply current to the voltage follower circuit when a potential difference between the second one of the differential input terminals and the output terminal is equal to or higher than a predetermined value.

Claims

1. An amplifier, comprising:

a voltage follower circuit that includes a first input terminal, a second input terminal, and an output terminal which is connected to said second input terminal;

a first current source configured to supply a first current to said voltage follower circuit;

a second current source configured to supply a second current to said voltage follower circuit,

wherein said second current source comprises a first PMOS transistor and a second PMOS transistor,

wherein a drain terminal of said first PMOS transistor and a drain terminal of said second PMOS transistor are directly connected to said voltage follower circuit,

wherein a gate terminal of said first PMOS transistor is directly connected to said first input terminal;

an input voltage supplied to said first input terminal and said second current source; and

an output voltage, output from said output terminal,

wherein said second current source is configured to supply said second current in an event a difference between said input voltage and said output voltage is larger than a first predetermined voltage.

2. The amplifier according to claim 1,

wherein said second current source is configured to supply a third current to said voltage follower circuit in an event the difference between said output voltage and said input voltage is less than a second predetermined voltage.

3. A liquid crystal displaying driving circuit for outputting a driving signal for driving pixels provided in a liquid crystal displaying section operative to display an image, said liquid crystal displaying driving circuit comprising:

a digital-to-analog conversion circuit configured to generate a driving analog signal in response to an input video signal; and

an amplifier including;

a voltage follower circuit that includes a first input terminal, a second input terminal, and an output terminal which is connected to said second input terminal, wherein said voltage follower circuit is configured to;

amplify said driving analog signal input to said first input terminal, and

output said amplified driving analog signal from said output terminal,

a first current source configured to supply a first current to said voltage follower circuit, and

a second current source configured to supply a second current to said voltage follower circuit,

wherein said second current source comprises a first PMOS transistor and a second PMOS transistor,

wherein a drain terminal of said first PMOS transistor and a drain terminal of said second PMOS transistor are directly connected to said voltage follower circuit,

wherein a gate terminal of said first PMOS transistor is directly connected to said first input terminal,

wherein said driving analog signal is input to said second current source, and

wherein said second current source is configured to supply said second current in an event a difference between an input voltage corresponding to said driving analog signal and an output voltage corresponding to said amplified driving analog signal is larger than a predetermined voltage.

4. A liquid crystal display apparatus, comprising:

a driving circuit including;

a decoder circuit configured to decode an input signal to produce an input video signal,

a digital-to-analog conversion circuit configured to generate a driving analog signal in response to said input video signal,

an amplification circuit including a plurality of amplifiers each including;

a voltage follower circuit that includes a first input terminal, a second input terminal, and an output terminal which is connected to said second input terminal, wherein said voltage follower circuit is configured to;

amplify said driving analog signal input to said first input terminal, and

output said amplified driving analog signal from said output terminal,

a first current source configured to supply a first current to said voltage follower circuit, and

a second current source configured to supply a second current to said voltage follower circuit,

wherein said second current source comprises a first PMOS transistor and a second PMOS transistor,

wherein a drain terminal of said first PMOS transistor and a drain terminal of said second PMOS transistor are directly connected to said voltage follower circuit,

wherein a gate terminal of said first PMOS transistor is directly connected to said first input terminal,

wherein said driving analog signal is input to said second current source, and

wherein said second current source is configured to supply said second current in an event a difference between an input voltage corresponding to said driving analog signal and an output voltage corresponding to said amplified driving analog signal is larger than a predetermined voltage; and

a liquid crystal displaying section including a plurality of pixels driven by said driving analog signal and configured to display an image.