Current source type current output circuit using current mirrors

• US 4,766,396 A
• Filed: 08/07/1987
• Issued: 08/23/1988
• Est. Priority Date: 08/28/1986
• Status: Expired due to Term

• Current Assignee: OKI Electric Industry Company Limited
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Taya, Takashi, Tahara, Toshiyuki
• Primary Examiner(s): Mullins, James B.
• Application Number:
  US07/082,648
• Time in Patent Office: 382 Days
• Field of Search: 330/105, 330/106, 330/257, 330/260, 330/288, 330/293, 323/315, 323/316
• US Class Current: 330/288
• CPC Class Codes: H03F 3/343 with semiconductor devices only

Abstract

A current source type current output circuit for applying to a load a current which is proportional to an input includes an amplifier of the type receiving a current and producing a voltage, and a feedback circuit for feeding back an output of the amplifier to an input terminal of the amplifier. The feedback circuit is made up of a first, a second, and a third current mirror circuit, and a first, a second, and a third resistor. An output terminal of the amplifier is connected to an input terminal of the second current mirror circuit via the third resistor and to an input terminal of the first current mirror circuit via a series connection of the first and second resistors. The load is connected to the intermediate point of the serial connection of the first and second resistors. An output terminal of the second current mirror circuit is connected to an input terminal of the third current mirror circuit. Output terminals of the first and third current mirror circuits are connected to an input terminal of the amplifier such that a current which is proportional to an input is fed to the load. A reference terminal of each of the first and second current mirror circuits is connected to a first power source, and a reference terminal of the third current mirror circuit is connected to a second power source.

Claims

1. A current source type current output circuit for applying to a load a current which is proportional to an input, comprising:

an amplifier of a type receiving a current and producing a voltage; and

a feedback circuit for feeding back an output of said amplifier to an input terminal of said amplifier;

said feedback circuit comprising a first, a second, and a third current mirror circuit, and a first, a second, and a third resistor;

an output terminal of said amplifier being connected to an input terminal of said second current mirror circuit via said third resistor and to an input terminal of said first current mirror circuit via a series connection of said first and second resistors;

the load being connected to an intermediate point of said serial connection of said first and second resistors;

an output terminal of said second current mirror circuit being connected to an input terminal of said third current mirror circuit;

an output terminal of said first current mirror circuit and an output terminal of said third current mirror circuit being connected to said input terminal of said amplifier such that a current which is proportional to an input is fed to the load;

a reference terminal of each of said first and second current mirror circuits being connected to a first power source, and a reference terminal of said third current mirror circuit being connected to a second power source.

2. A current output circuit in accordance with claim 1, wherein said amplifier is provided with a significantly extremely large amplification gain, and a sum of resistance values of said first and second resistors is substantially equal to a resistance value of said third resistor.

3. A current output circuit in accordance with claim 2, wherein said input signal current is applied to at least one of said input terminals of said first, second and third current mirror circuits.

4. A current source type current output circuit for applying to a load a current which is proportional to an input, comprising:

a first, a second, and a third input terminal for receiving the input;

a first output terminal to which the load is connected;

an amplifier means having a negative transresistance an absolute value of which is large and comprising a fourth input terminal for receiving a current, and a second output terminal for producing a voltage; and

a feedback means for feeding back an output from said second output terminal to said fourth input terminal;

said feedback means comprising a first, a second, and a third current mirror circuit, and a first, a second, and a third resistor;

said first resistor connecting said second output terminal to said first output terminal;

said third resistor having a resistance value which is substantially equal to a sum of resistance values of said first and second resistors;

said first current mirror circuit having an input which is connected to said first output terminal via said second resistor, and to said first terminal, an output connected to said fourth input terminal, and a reference terminal connected to a first power source;

said second current mirror circuit having an input which is connected to said second output terminal via said third resistor, and to said second input terminal, an output which is connected to said third input terminal, and a reference terminal which is connected to said first power source;

said third current mirror circuit having an input which is connected to said third input terminal, an output which is connected to said fourth input terminal, and a reference terminal which is connected to a second power source.