| US 7,502,059 B2 | ||
| Asymmetric comparator for use in pixel oversaturation detection | ||
| Sandor L. Barna, Pasadena, Calif. (US) | ||
| Assigned to Aptina Imaging Corporation, Grand Cayman (Cayman Islands) | ||
| Filed on Aug. 22, 2002, as Appl. No. 10/225,170. | ||
| Prior Publication US 2004/0036783 A1, Feb. 26, 2004 | ||
| Int. Cl. H04N 5/217 (2006.01); H04N 3/14 (2006.01); H04N 5/335 (2006.01); H03K 5/22 (2006.01) | ||
| U.S. Cl. 348—300 [348/241; 327/65] | 14 Claims |
| 1. An asymmetric comparator for use in a pixel sampling circuit, comprising:
a differential transistor pair of a first conductivity type, wherein the gate of a first transistor of said differential pair
is connected at an input of said comparator to receive a pixel image signal and the gate of a second transistor of said differential
pair is connected to receive a ground voltage potential, said gate of said first transistor of said differential pair providing
a first switching threshold for said comparator;
said first of said transistors of said differential pair having a conduction characteristic different from that of said second
transistor of said differential pair;
a pair of cross-coupled transistors of a second conductivity type for use as current sources, each of said pair of cross-coupled
transistors of said second conductivity type being serially connected with a respective one of said differential pair of transistors
of said first conductivity type, the gates of said pair of cross-coupled transistors being disconnected from each other; and
an output terminal coupled to a node serially interconnecting said first transistor of said differential pair to a gate of
a first of the pair of cross-coupled transistors.
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