Low voltage current sources/current mirrors
AssigneeFreescale Semiconductor, Inc.
InventorRadu M. Secareanu
Life of this patent
Estimating the term…
Abstract
A current generator circuit and method capable of operating with a power supply voltage of less than two VT utilizing a reference transistor and a buffer transistor, each transistor having a source, a drain, and a gate, the drain of the reference transistor coupled to the source of the buffer transistor, the drain of the buffer transistor adapted to be coupled to a power supply, a bias circuit coupled to the drain of the reference transistor and the source of the buffer transistor, and an amplifier coupled to the bias circuit to provide a feedback voltage substantially independent of the voltage of the power supply and sufficient to maintain the reference transistor in constant bias.
Claims14
A current generator circuit having an output for providing a reference current comprising:
- a first reference transistor of a first type having a gate coupled for receiving a reference voltage, a drain, and a source coupled for receiving a first power supply voltage;
- a second reference transistor of said first type having a gate coupled for receiving said reference voltage, a drain, and a source coupled for receiving said first power supply voltage;
- a bias transistor of a second type having a gate coupled to said drain of said first reference transistor, a drain coupled to said drain of said second reference transistor, and a source coupled for receiving a second power supply voltage;
- and
- a buffer transistor of said first type having a gate coupled to said drain of said second reference transistor, a drain coupled to the output of the current generator circuit, and a source coupled to said drain of said first reference transistor.
A current generator circuit having an output for providing a reference current comprising:
- a first transistor of a first type having a first electrode coupled to the output of the current generator circuit, a control electrode, and a second electrode;
- a second transistor of said first type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled for receiving a first reference voltage, and a second electrode coupled for receiving a first power supply voltage;
- a third transistor of said first type having a first electrode coupled to said control electrode of said first transistor, a control electrode coupled for receiving said first reference voltage, and a second electrode coupled for receiving said first power supply voltage;
- a fourth transistor of a second type having a first electrode coupled to said first electrode of said third transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode;
- a fifth transistor of said second type having a first electrode coupled to said second electrode of said fourth transistor, a control electrode, and a second electrode coupled for receiving a second power supply voltage;
- and
- a first amplifier having an input coupled to said first electrode of said fifth transistor and an output coupled to said control electrode of said fifth transistor.
A current generator circuit having an output for providing a reference current comprising:
- a first transistor of a first electrode coupled to the output of the current generator circuit, a control electrode, and a second electrode;
- a second transistor of said first type having a first electrode coupled to said second electrode of said first transistor, a control electrode coupled for receiving a first power supply voltage;
- a third transistor of said first type having a first electrode, a control electrode coupled for receiving said first reference voltage, and a second electrode coupled for receiving said first power supply voltage;
- a fourth transistor of a second type having a first electrode coupled to said first electrode of said third transistor, a control electrode coupled to said first electrode of said second transistor, and a second electrode;
- a fifth transistor of said second type having a first electrode coupled to said second electrode of said fourth transistor, a control electrode, and a second electrode coupled for receiving a second power supply voltage;
- a first amplifier having an input coupled to said first electrode of said fifth transistor and an output coupled to said control electrode of said fifth transistor;
- and
- a second amplifier having an input coupled to said first electrode of said third transistor and an output coupled to said control electrode of said first transistor.
Dependencies are inferred from the claim text.