Low power voltage reference with improved line regulation
AssigneeMicrel, Inc.
InventorPhilip W. Yee
Life of this patent
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Abstract
A voltage reference circuit includes a first transistor and a second transistor having their control terminals connected together, a first resistor coupled to a first current handling terminal of the first transistor, a second resistor coupled between an output node and a second current handling terminal of the second transistor, and a current mirror. The reference circuit provides an output voltage that is independent of variations in the supply voltage by adjusting the resistance of the first resistor in response to changes in the supply voltage. In one embodiment, the voltage at the control terminals of the first and second transistors is kept constant despite variations in the supply voltage. A first current and a second current flowing through the first and second transistors are also kept constant.
Claims45
A voltage reference circuit comprising:
- a current mirror electrically coupled to a first supply voltage, said current mirror having a first current terminal and a second current terminal;
- a first transistor having a first current handling terminal, a second current handling terminal coupled to said first current terminal of said current mirror, and a control terminal;
- a second transistor having a first current handling terminal coupled to a second supply voltage, a second current handling terminal, and a control terminal coupled to said second current handling terminal, said control terminal also coupled to said control terminal of said first transistor;
- a first resistor coupled between said first current handling terminal of said first transistor and said second supply voltage, said first resistor having a variable resistance, said resistance being modulated by a first bias voltage related to said first supply voltage;
- and
- a second resistor coupled between said second current terminal of said current mirror and said second current handling terminal of said second transistor.
A voltage reference circuit comprising:
- a current mirror electrically coupled to a first supply voltage, said current mirror having a first current terminal and a second current terminal;
- a first transistor having a first current handling terminal coupled to a second supply voltage, a second current handling terminal coupled to said first current terminal of said current mirror, and a control terminal;
- a second transistor having a first current handling terminal coupled to said second supply voltage, a second current handling terminal coupled to said control terminal of said first transistor, and a control terminal coupled to a first node;
- a first resistor coupled between said second current handling terminal of said second transistor and said first node, said first resistor having a variable resistance, said resistance being modulated by a first bias voltage related to said first supply voltage;
- and
- a second resistor coupled between said first node and said second current terminal of said current mirror.
A voltage reference circuit comprising:
- a current mirror electrically coupled to a first supply voltage, said current mirror having a first current terminal and a second current terminal, said second current terminal providing a reference voltage;
- a first transistor having a first current handling terminal coupled to a second supply voltage, a second current handling terminal coupled to said first current terminal of said current mirror, and a control terminal;
- a second transistor having a first current handling terminal coupled to said second supply voltage, a second current handling terminal coupled to said control terminal of said first transistor, and a control terminal coupled to a first node;
- a first resistor coupled between said second current handling terminal of said second transistor and said first node, said first resistor having a variable resistance, said resistance being modulated by said first supply voltage;
- a second resistor coupled between said first node and a second node, said second resistor having fixed resistance;
- and
- a third resistor coupled between said second node and said second current terminal of said current mirror, said third resistor having a variable resistance, said resistance being modulated by said first supply voltage.
Dependencies are inferred from the claim text.