Adjustable gain current amplifiers
First Claim
Patent Images
1. A current mirror amplifier including:
- an input terminal for receiving an input current;
an output terminal;
first and second transistors, each having base and emitter and collector electrodes and being operated within the confines of an integrated circuit at an absolute temperature substantially equal to T;
first conductive means connecting the collector electrode of said first transistor to said input terminal;
second conductive means connecting the collector electrode of said second transistor to said output terminal;
a collector-to-base feedback connection between the collector and base electrodes of said first transistor for adjusting the base potential of said first transistor to condition said first transistor to conduct as collector current substantially all of said input current; and
means for applying substantially the same potential to the base electrode of said second transistor as said collector-to-base feedback connection applies to the base electrode of said first transistor, said current mirror amplifier having in combination therewith, means for adjusting its current gain to values substantially independent of T, which means for adjusting its current gain consists of;
a source of adjustable offset voltage proportional to T applied between the emitter electrodes of said first and said second transistor.
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Abstract
The current gain of a current mirror amplifier (CMA) is trimmed by applying an adjustable potential difference between the base-emitter potentials of first and second transistors of the CMA, this potential difference being substantially linearly proportional to the absolute temperature at which the first and second transistors are operated. The resultant trim maintains itself over a wide range of temperature.
11 Citations
9 Claims
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1. A current mirror amplifier including:
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an input terminal for receiving an input current; an output terminal; first and second transistors, each having base and emitter and collector electrodes and being operated within the confines of an integrated circuit at an absolute temperature substantially equal to T; first conductive means connecting the collector electrode of said first transistor to said input terminal; second conductive means connecting the collector electrode of said second transistor to said output terminal; a collector-to-base feedback connection between the collector and base electrodes of said first transistor for adjusting the base potential of said first transistor to condition said first transistor to conduct as collector current substantially all of said input current; and means for applying substantially the same potential to the base electrode of said second transistor as said collector-to-base feedback connection applies to the base electrode of said first transistor, said current mirror amplifier having in combination therewith, means for adjusting its current gain to values substantially independent of T, which means for adjusting its current gain consists of; a source of adjustable offset voltage proportional to T applied between the emitter electrodes of said first and said second transistor. - View Dependent Claims (2, 3)
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4. A current mirror amplifier including:
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an input terminal for receiving an input current; an output terminal; first and second transistors, each having base and emitter and collector electrodes and being operated at an absolute temperature substantially equal to T; first conductive means connecting the collector electrode of said first transistor to said input terminal; second conductive means connecting the collector electrode of said second transistor to said output terminal; a collector-to-base feedback connection between the collector and base electrodes of said first transistor for adjusting the base potential of said first transistor to condition said first transistor to conduct as collector current substantially all of said input current; and means for applying substantially the same potential to the base electrode of said second transistor as said collector-to-base feedback connection applies to the base electrode of said first transistor; and means for adjusting the gain of said current mirror amplifier as between its input and output terminals, which means consists of means for adjusting, independently of the current flow through the respective emitter-to-collector paths of said first and second transistors, the potential between the emitter electrodes of said first and said second transistors. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification