Differential current mirror system and method
AssigneeNational Semiconductor Corporation
InventorsAbhijit M. Phanse, Michael X. Maida
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Abstract
There is disclosed a differential current mirror system and method for providing differential output current signals that are proportional to differential input current signals in which common mode current signals are rejected. The system comprises a pair of diode connected transistors and a differential amplifier. The pair of diode connected transistors comprises a first and second transistor coupled together. The differential amplifier comprises a third and fourth transistor coupled together in a differential amplifier configuration. The gate of the third transistor receives a first input current signal from the drain of the first transistor and the gate of the fourth transistor receives a second input current signal from the drain of the second transistor.
Claims20
A differential current mirror system capable of rejecting a common mode input current signal comprising:
- a pair of diode connected transistors comprising a first transistor and a second transistor coupled together in a common mode rejection configuration;
- a differential amplifier coupled to said pair of diode connected transistors, said differential amplifier comprising a third transistor and a fourth transistor coupled together, wherein the gate of said third transistor is coupled to the drain of said first transistor, and wherein the gate of said fourth transistor is coupled to the drain of said second transistor;
- and
- a fifth transistor coupled to said pair of diode connected transistors;
- wherein said differential current mirror system is capable of multiplying an alternating current input signal current by a ratio of a transconductance of said differential amplifier to a transconductance of said pair of diode connected transistors to obtain an alternating current output signal current in which said common mode input current signal is rejected.
For use in a differential current mirror system, a method for providing differential output current signals that are proportional to differential input current signals in which a common mode input current signal is rejected comprising the steps of:
- coupling together a first transistor and a second transistor to form a pair of diode connected transistors in a common mode rejection configuration;
- coupling a differential amplifier to said pair of diode connected transistors, wherein said differential amplifier comprises a third transistor and a fourth transistor in which the gate of said third transistor is coupled to the drain of said first transistor, and in which the gate of said fourth transistor is coupled to the drain of said second transistor;
- coupling a fifth transistor to said pair of diode connected transistors;
- multiplying an alternating current input signal current by a ratio of a transconductance of said differential amplifier to a transconductance of said pair of diode connected transistors;
- and
- obtaining an alternating current output signal current in which said common mode input current signal is rejected.
Dependencies are inferred from the claim text.