Current mirror circuit
First Claim
1. A current mirror having an input for receiving a reference current and an output for providing an output current, the current mirror comprising:
- a first resistor having a first terminal coupled to a first power supply terminal and a second terminal coupled to the input of the current mirror;
a first transistor of a first conductivity type having a first electrode coupled to said first power supply terminal, a control electrode coupled to the input of the current mirror, and a second electrode;
a second transistor of a second conductivity type having a first electrode, a control electrode coupled to said second electrode of said first transistor, and a second electrode;
a second resistor having a first terminal coupled to said second electrode of said second transistor and a second terminal coupled to said first power supply terminal;
a third transistor of said first conductivity type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode coupled to a second power supply terminal; and
a fourth transistor of said second conductivity type having a first electrode coupled to said second power supply terminal, a control electrode coupled to said second power supply terminal, and a second electrode coupled to said first electrode of said second transistor.
18 Assignments
0 Petitions
Accused Products
Abstract
A current mirror circuit (31) that includes an active loop which operates transistors of different conductivity type at equal base-emitter junction voltages to minimize error. A first resistor (38) couples to a base of a first transistor (32) of a first conductivity type in a voltage follower configuration. A reference current is coupled to the first resistor (38). The voltage across the first resistor (38) and base-emitter junction of the first transistor (32) is mirrored across the base-emitter junction of a second transistor (34) of a second conductivity type and a second resistor (39). A third transistor (35) of the second conductivity type in a diode configuration is coupled to receive current from the second transistor (34). The voltage across the third transistor (35) biases a fourth transistor (33) of a first conductivity type. The current from the fourth transistor (33) is provided to the first transistor such that the first and second transistors (32,34) operate at equal base-emitter voltages.
12 Citations
19 Claims
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1. A current mirror having an input for receiving a reference current and an output for providing an output current, the current mirror comprising:
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a first resistor having a first terminal coupled to a first power supply terminal and a second terminal coupled to the input of the current mirror; a first transistor of a first conductivity type having a first electrode coupled to said first power supply terminal, a control electrode coupled to the input of the current mirror, and a second electrode; a second transistor of a second conductivity type having a first electrode, a control electrode coupled to said second electrode of said first transistor, and a second electrode; a second resistor having a first terminal coupled to said second electrode of said second transistor and a second terminal coupled to said first power supply terminal; a third transistor of said first conductivity type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode coupled to a second power supply terminal; and a fourth transistor of said second conductivity type having a first electrode coupled to said second power supply terminal, a control electrode coupled to said second power supply terminal, and a second electrode coupled to said first electrode of said second transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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- 12. A method of increasing accuracy of a current mirror wherein the current mirror comprises transistors of different conductivity type, the method including a step of operating the transistors of different conductivity type having identical base-emitter junction voltages to minimize current mirror error.
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17. A current mirror having an input for receiving a reference current and an output for providing an output current, the current mirror comprising:
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a first resistor having a first terminal coupled to a first power supply terminal and a second terminal coupled to the input of the current mirror; a first transistor of a first conductivity type having a first electrode coupled to said first power supply terminal, a control electrode coupled to the input of the current mirror, and a second electrode; a second transistor of a second conductivity type having a first electrode, a control electrode coupled to said second electrode of said first transistor, and a second electrode; second resistor having a first terminal coupled to said second electrode of said second transistor and a second terminal coupled to said first power supply terminal; a third transistor of said first conductivity type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode coupled to a second power supply terminal; a fourth transistor of said second conductivity type having a first electrode coupled to said second power supply terminal, a control electrode coupled to said second power supply terminal, and a second electrode coupled to said first electrode of said second transistor; a fifth transistor of said second conductivity type having a first electrode coupled to the output of the current mirror, a control electrode coupled to said second electrode of said first transistor, and a second electrode; and a third resistor having a first terminal coupled to said second electrode of said first transistor and a second terminal coupled to said first power supply terminal.
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18. A current mirror having an input for receiving a reference current and an output for providing an output current, the current mirror comprising:
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a first resistor having a first terminal coupled to a first power supply terminal and a second terminal coupled to the input of the current mirror; a first transistor of a first conductivity type having a first electrode coupled to said first power supply terminal, a control electrode coupled to the input of the current mirror, and a second electrode; a second transistor of a second conductivity type having a first electrode, a control electrode coupled to said second electrode of said first transistor, and a second electrode; a second resistor having a first terminal coupled to said second electrode of said second transistor and a second terminal coupled to said first power supply terminal; a third transistor of said first conductivity type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode coupled to a second power supply terminal; and a fourth transistor of said second conductivity type having a first electrode coupled to the output of the current mirror, a control electrode coupled to said second electrode of said third transistor, and a second electrode coupled to said first electrode of said second transistor. - View Dependent Claims (19)
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Specification