Biasing scheme for low supply headroom applications
AssigneeBroadcom Corporation
InventorsArya Reza Behzad, Frank Wayne Singor
Life of this patent
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Abstract
Methods and apparatus for improving the current matching within current mirror circuits in applications such as low voltage integrated circuits. Embodiments of the present invention attempt to maintain the proper current ratio between reference and output supplies by adjusting the reference output of the current mirror. An existing reference voltage on the output side of the mirror can be used or a reference voltage can be created to be used for the voltage regulation of the reference side of the current mirror.
Claims18
A method of providing proportional currents in a current mirror, the method comprising:
- providing a current mirror having a reference current side which provides a reference current, and a load current side which provides a load current;
- detecting an indication within the load current side of the current mirror that the load current is decreasing;
- and
- decreasing the reference current proportional to a decrease in the load current.
An apparatus for producing a load current proportional to a reference current, the apparatus comprising:
- a reference current generator that produces a reference current;
- a load current generator that produces a load current proportional to the reference current;
- a sense circuit for sensing at least one parameter indicative of the load current and producing a control voltage from said at least one parameter;
- and
- a circuit that decreases the reference current proportional to the control voltage.
A circuit to improve tracking in a current mirror having a reference current side and a load current side, the reference current side having a reference current side impedance and the load current side having a load current side impedance, the circuit comprising:
- a semiconductor device through which the load current passes;
- a semiconductor device through which the reference current passes;
- and
- a circuit coupled to the output circuit which adjusts the voltage across the reference semiconductor device to match the voltage across the load semiconductor device.
Dependencies are inferred from the claim text.