TC236P Datasheet, PDF (9/17 Pages) Texas Instruments – 680-×500-PIXEL CCD IMAGE SENSOR

ODB
IAG1, 2
SAG
SRG
RST
Clear
Integrate
1 µs Min
Transfer to Memory
TC236P
680- × 500-PIXEL CCD IMAGE SENSOR
SOCS055A – JUNE 1996 – REVISED APRIL 1997
Readout
500 Pulses
500 Pulses
250 Cycles
500 Pulses
684 Pulses
Expanded Section of
Parallel Transfer
IAG1, 2
SAG
SRG
684 Pulses
Figure 8 . Progressive-Scan Timing Diagram With Dual-Register Readout
serial registers
The storage-area gate and serial gate(s) are used to transfer the charge line by line from the storage area into
the serial register(s). Depending on the readout mode, one or both serial registers is used. If both are used, the
registers are read out in parallel.
readout and video processing
After transfer into the serial register(s), the pixels are read out and placed onto a charge-detection node. The
node must be reset to a reference level before the next pixel is placed onto the detection node. The timing for
the serial-register readout, which includes the external pixel clamp and sample-and-hold signals needed to
implement correlated double sampling (CDS), is shown in Figure 9. As the charge is transferred onto the
detection node, the potential of this node changes in proportion to the amount of signal received. The change
is sensed by an MOS transistor and, after proper buffering, the signal is supplied to the output terminal of the
image sensor. The buffer amplifier converts charge into a video signal. Figure 10 shows the circuit diagram of
the charge-detection node and output amplifier. The detection nodes and amplifiers are placed a short distance
away from the edge of the storage area; therefore, each serial register contains four dummy elements that are
used to span the distance between the serial registers and the amplifiers.
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