Biasing current to speed up current mirror settling time
AssigneeAtmel Corporation
InventorsGabriele Pelli, Lorenzo Bedarida, Massimiliano Frulio, Andrea Bettini
Life of this patent
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Abstract
A current mirror circuit includes a first current-mirror transistor coupled to a second current-mirror transistor. A load is coupled to the second current-mirror transistor. A first current source is coupled to the first current-mirror transistor to cause a bias current to flow through the first current-mirror transistor and a second current source is coupled to the second current-mirror transistor and in parallel with the load to shunt the bias current away from the load.
Claims23
A current mirror circuit including:
- a diode-connected current-mirror transistor driven by a current source and coupled to a driven current-mirror transistor;
- a load coupled to the driven current-mirror transistor;
- a first bias current source coupled to the diode-connected current-mirror transistor to cause a bias current to flow through the diode-connected current-mirror transistor;
- and
- a second bias current source coupled to the driven current-mirror transistor and in parallel with the load to shunt the bias current away from the load.
A current-mirror circuit including:
- a first current-mirror stage including a diode-connected current-mirror transistor of a first conductivity type driven by a current source coupled to a driven current-mirror transistor of the first conductivity type;
- a second current-mirror stage including a diode-connected current-mirror transistor of a second conductivity type driven by current through the driven current-mirror transistor of the first conductivity type and coupled to a driven current-mirror transistor of the second conductivity type;
- a load coupled to the driven current-mirror transistor of the second conductivity type;
- a first bias current source coupled to the diode-connected current-mirror transistor of the first conductivity type to cause a bias current to flow through the diode-connected current-mirror transistor of the first conductivity type;
- and
- a second bias current source coupled to one of the diode-connected current-mirror transistor of a second conductivity type and the driven current-mirror transistor of a second conductivity type so as to subtract the bias current from current flowing in the load.
7-9. (canceled)
A current-mirror circuit including:
- a first current-mirror stage including a diode-connected current-mirror transistor of a first conductivity type driven by a current source coupled to a driven current-mirror transistor of the first conductivity type;
- a second current-mirror stage including a diode-connected current-mirror transistor of a second conductivity type driven by current through the driven current-mirror transistor of the first conductivity type and coupled to a driven current-mirror transistor of the second conductivity type;
- a load coupled to the driven current-mirror transistor of the second conductivity type;
- a first bias current source coupled to the diode-connected current-mirror transistor of the first conductivity type to cause a first bias current to flow through the diode-connected current-mirror transistor of the first conductivity type;
- a second bias current source coupled to the diode-connected current-mirror transistor of a second conductivity type and in parallel with the driven current-mirror transistor of the first conductivity type to shunt the first bias current away from the driven current-mirror transistor of the first conductivity type;
- a third bias current source coupled to the diode-connected current-mirror transistor of the second conductivity type to cause a second bias current to flow through the diode-connected current-mirror transistor of the second conductivity type;
- and
- a fourth bias current source coupled to the driven current-mirror transistor of a second conductivity type and in parallel with the load to shunt the second bias current away from the load.
A method of operating a current mirror circuit including a diode-connected transistor passing an input current and driving a driven transistor forcing current through a load, the method including:
- causing a bias current to flow in the diode-connected transistor;
- and
- subtracting the bias current from the current flowing from the driven transistor into the load.
A method of operating a current mirror circuit including a first current-mirror stage including a diode-connected current-mirror transistor of a first conductivity type passing an input current and coupled to a driven current-mirror transistor of the first conductivity type, a second current-mirror stage including a diode-connected current-mirror transistor of a second conductivity type driven by current through the driven current-mirror transistor of the first conductivity type and coupled to a driven current-mirror transistor of the second conductivity type, and a load coupled to the driven current-mirror transistor of the second conductivity type, the method including:
- causing a bias current to flow in the diode-connected transistor of the first conductivity type;
- and
- subtracting the bias current from one of the current flowing from the driven transistor of the first conductivity type into the diode-connected transistor of the first conductivity type and the current flowing from the driven transistor of the second conductivity type into the load.
18-19. (canceled)
Dependencies are inferred from the claim text.