Motorola Corporation

Deborah J Beckwith

Barry B Heim

Kendall G Moore

Frederic B Shapiro

Michael W Hodel

Paul T Hu

Freeman D Colbert

MonaLisa Morgan

A sensing circuit (202) uses correlated double sampling to sample a first pixel signal of a pixel stream (V.sub.PIXEL) at two different times to produce a dark signal and a light signal on two capacitors (310, 314). The dark and light signals are amplified in an amplifier (302) to produce a differential output signal (V.sub.PP -V.sub.PN) proportional to their difference. While the samples of the first pixel signal are being amplified, a second pixel signal is double-sampled to produce dark and light signals on two other capacitors (312, 316) for amplifying in the same amplifier. The period of the pixel signal is divided into time slots (T.sub.1 -T.sub.16) by a clocked oscillator (52). Programming signals (PROG1, PROG2) control the time slots in which sampling control pulses (V.sub.S1, V.sub.S2) are generated.

Sensing circuit for capturing a pixel signal

A mixed mode buffer circuit 11 including a first input (12), a second input (13), and an output (14). A voltage exceeding a supply voltage of mixed mode buffer circuit 11 can be applied to the output (14) without latchup or an increase in leakage current. The mixed mode buffer includes an output transistor (24) of a first conductivity type having a first electrode coupled to the output (14), a control electrode coupled to the first input (12), a second electrode coupled for receiving the supply voltage, and a bulk electrode. A first transistor (19) biases the bulk electrode when the voltage at the output is within a first predetermined range. A first bulk bias circuit (28) biases the bulk electrode when the output voltage is within a second predetermined range. A second bulk bias circuit (27) and a second transistor (18) couples the voltage at the output to the bulk electrode and the control electrode respectively, when the output voltage exceeds the second predetermined range.

CMOS output driver which can tolerate an output voltage greater than the

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Chandler, AZ, United States of America

Deborah J Beckwith