Sanyo VPC X 360 E, VPC-X360, VPC-X360EX 5. Transfer of Electric Charge by the Horizontal CCD, Fig. 1-6.Theory of Signal Extraction Operation

5. Transfer of Electric Charge by the Horizontal CCD

The transfer system for the horizontal CCD emplays a 2-phase drive method.

The electric charges sent to the final stage of the horizontal CCD are transferred to the floating diffusion, as shown in Fig. 1-5. RG is turned on by the timing in (1), and the floating diffusion is charged to the potential of PD. The RG is turned off by the timing in (2). In this condition, the floating diffusion is floated at high impedance. The H1 potential becomes shallow by the timing in (3), and the electric charge now moves to the floating diffusion.

Here, the electric charges are converted into voltages at the rate of V = Q/C by the equivalent capacitance C of the floating diffusion. RG is then turned on again by the timing in (1) when the H1 potential becomes deep.

Thus, the potential of the floating diffusion changes in proportion to the quantity of transferred electric charge, and becomes CCD output after being received by the source follower. The equivalent circuit for the output circuit is shown in Fig. 1-6.

(1)

(2)

(3)

H1	H2	H1	H2	H1 HOG	RG
							CCD OUT
						PD		(1) (2)	(3)
			Floating diffusion				H1	3.5V
								0V
H1	H2	H1	H2	H1 HOG	RG			3.5V
							H2
								0V
							CCD OUT
						PD		13.5V
							RG	0V
H1	H2	H1	H2	H1 HOG	RG				RG pulse leak signal
							CCD OUT
									Black level
							CCD OUT
									Signal voltage

Fig. 1-5. Horizontal Transfer of CCD Imager and Extraction of Signal Voltage

Reset gate pulse 12V Pre-charge drain bias（PD）

Direction of transfer

H Register

Voltage output

Electric charge

Floating diffusion gate is floated at a high impedance.

C is charged equivalently

Fig. 1-6. Theory of Signal Extraction Operation

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