PI3033B Просмотр технического описания (PDF) - AMI Semiconductor

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производитель

PI3033B

Contact Image Sensor

AMI Semiconductor 

Preliminary PI3033B datasheet

Signal Conversion Circuit

Figure 5. Video Output Test and Application Circuit

Figure 5, Video Output Test and Application Circuit shows a simply circuit that provides the cleanest

technique in processing the video output. It integrates all the currents from each pixel element onto a

capacitor, CAP. Then the CAP is reset to zero volts by activating the shunt switch, SW, and

connecting the video line to ground prior to accessing the following pixel element. Simultaneous to

SW activation, the pixel element storage is, also, reset to the dark level, hence initialized for the new

pixel integration process. Since this process sums the switch edges and signal current pulses onto the

CAP, it minimizes the switching patterns on the video pixels. The summed charges stored in the CAP,

produces a pixel voltage with amplitude proportional to the charge from the current pulse. Since

switching energies are high frequencies components, they tend to integrate to a 0 value and the

remainder adds a constant value to the dark level. The signal pixels Vp(n) is referenced to the Dark

Level as it is seen in Figure 6, Single Pixel Output Voltage that depicts the typical pixel waveform.

Figure 6. Single Pixel Video Output

To measure these device’s parameters the value of the CAP is set to 100pf. This value includes the

stray capacitance of the video line. The value of RIN in the amplifier circuit is set to infinity, it is

removed, accordingly, the amplifier gain is one, hence serving as buffer amplifier, EL2044, AD8051 or

equivalent, to isolate the video line.

Page 7 of 13 Date: 03/18/05

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