Photodetection system and circuit for amplification
AssigneeCapella Microsystems, Inc.
InventorsBrian N. Kuo, Ing-Jye Lan, Koon Wing Tsang, Pei-Ling Hsu
Life of this patent
Estimating the term…
Abstract
A first device comprising a first current mirror is used to amplify the output of a first photodetector. A second device comprising a current mirror arrangement is employed to amplify the output of a second photodetector. The outputs of the two devices are then compared to provide a signal useful for many applications, including that for determining the position of a rotating member or of a member in relative motion to another member. Preferably, no feedback action is used for the amplification of the output of at least one of the photodetectors.
Claims15
An apparatus for amplifying an output of a photodetector, comprising:
- a first circuit path comprising a first transistor, a current from said photodetector being supplied to the first circuit path;
- and
- a second circuit path comprising a second transistor, said two transistors connected to form a current mirror arrangement, said two transistors being such that the current mirror arrangement provides a signal that is an amplified version of the output of the photodetector.
A photodetection apparatus, comprising:
- a first photodetector;
- a first device comprising:
- (a) a first circuit path comprising a first transistor, a current from said first photodetector being supplied to the first circuit path;
- and
- (b) a second circuit path comprising a second transistor, said two transistors connected to form a current mirror arrangement, said first and second transistors being such that the current mirror arrangement provides for the first device an output signal that is an amplified version of the output of the first photodetector;
- a second photodetector;
- and
- a second device comprising:
- (c) a third circuit path comprising a third transistor, a current from said second photodetector being supplied to the third circuit path;
- and
- (d) a fourth circuit path comprising a fourth transistor, said third and fourth transistors connected to form a current mirror arrangement, said third and fourth transistors being such that the current mirror arrangement provides for the second device an output signal that is an amplified version of the output of the second photodetector.
A photodetection apparatus, comprising:
- a first photodetector;
- a first circuit path comprising a first transistor, a current from said first photodetector being supplied to the first circuit path;
- a second photodetector;
- and
- a second circuit path comprising a second transistor, a current from said second photodetector being supplied to the second circuit path, wherein there is no feedback path in at least one of the two circuit paths.
Dependencies are inferred from the claim text.