| 摘要 |
PURPOSE: A drive circuit is provided to improve performance in a pixel cell or other circuit and to produce an output signal that is greater than a supply voltage and that provides suitable over-voltage protection. And also the drive circuit is provided to increase dynamic range and increase the rate at which stable states and reset levels are reached in a pixel cell. CONSTITUTION: Prior to a reset operation(defined by the transition from low to high and back to low again of the row reset signal), a drive capacitor(160) is charged, DRV switch(175) is open and RSTB is high(driving the output of inverter(154) low). As a reset operation begins, the voltage level at node(170) is settled at approximately 0.7V (one diode drop) below VDD, DRV switch(175) is open, and the INT switch is closed, holding the row reset line low. The INT switch(185) is then opened while the DRV switch(175) is simultaneously closed. This causes the voltage on the row reset line to rise to an equalized voltage level determined by charge transfer from drive capacitor(160) to the parasitic capacitance. The intermediate row reset voltage level equals approximately CD*(VDD-0.7)/(CRST + CD). The RSTB is then asserted(driven low) which raises the output of the inverter towards VDD. Row reset is then pulled low again by opening DRV switch(175) and closing INT switch(185). The RSTB signal is subsequently driven high in preparation of the next row reset operation. (Here, RSTB = reset strobe; INT = interrupt reset signal; DRV = drive reset signal and RRST = row reset signal)
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