JPS6010675A - Charge coupled device - Google Patents

Abstract

PURPOSE:To eliminate the induction noise generated in a floating region by varying the voltage applied to an output gate reversely in synchronization with the variation in the potential of a resetting gate. CONSTITUTION:A charge transfer unit is formed of an n<-> type region 12 on an n-well formed on a p type substrate 10, and transfer electrodes TG1-3, and the variation in the potential of the adjacent floating region FE to the n<-> type region under an output gate OG is detected by an output amplifier 15. The potentials which are displaced by 180 deg. out of phase are applied to the transfer electrodes by 2-phase drive system, the signal charge is transferred to the transfer electrode TG1 of the final stage, and transferred to the floating region FD. A reset gate RS is set to a high level to exhaust the signal charge stored in the region FE to a reset drain region RD. In this case, the gate OG is simultaneously set to low level, thereby preventing the generation of induction noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a charge-coupled device, and more particularly to a charge-coupled device that detects signal charges by a floating diffusion method.

[Technical background of the invention and its problems]

A conventional charge-coupled device has an output gate OG, a floating region FD, a reset gate R31, and a reset drain region RD adjacent to the final stage transfer electrode TG for transferring signal charges, so that the signal charges in the floating region FD are The output signal is obtained by detecting potential changes. The operation of this charge coupled device will be explained using FIG. 1 and FIG. 2. The signal charges 7a transferred to the final transfer electrode TG are accumulated in the potential well 5 generated by setting the final transfer electrode TG to a high level 5b at time t1. Next, when the final transfer electrode TG is changed to the low level 5a at time t2, the signal ``charge 7a'' exceeds the potential level 4a of the output gate OG and is transferred to the floating region FD.
Accumulated in floating area FD. This signal charge 7
After detecting the potential change due to a, the reset gate R8 is set to high level 2b at time t3, and the signal charge 7a is discharged to the reset drain region RD. By repeating the above operations, the transferred signal charges are detected one after another.

However, the output signal of the conventional charge-coupled device has a problem in that, in addition to the potential change caused by the signal charge, there is reset dielectric noise caused by the potential change of the reset gate R8. That is, as shown in FIG. 2, when the reset gate +-Its is changed from high level 2b to low level 2a at time t4, the output signal changes from level 3a to level 3b due to the change. Thereafter, at time t2, when the final transfer electrode TG becomes low level, the signal charge 7a is transferred, and the level of the output signal changes to 3c. In this way, in addition to the change caused by the signal charge 7a, the reset induced noise of the reset gate R8 is added. Although it is necessary to remove this reset induced noise, it has not been possible to remove it because its magnitude differs depending on the device and its frequency is very high.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a charge-coupled device that can obtain an output signal without reset-induced noise.

[Summary of the invention]

To achieve this objective, the charge-coupled device according to the present invention allows the voltage applied to the output gate to be varied in the opposite direction in synchronization with the reset gate. This cancels out induced changes occurring in the floating region.

[Practice of the invention]

A charge coupled device according to a central Mli example of the present invention is not shown in FIG. '1a load transfer section is formed on the P-type substrate 10.
“Region 12 in well 11 and transfer in insulating layer 13-@
It consists of L-TGI, TG2, and TG3.

At the final stage transfer gate, the output gate OG is disconnected by instantaneous contact with the rain TGI (formed in the hard layer 13. n- below the output gate OG).
Adjacent to the region, an n++ floating region FD1n region 14 that accumulates the transferred No. 1d charge and a reset drain region RD are formed. A reset gate R8 is formed in the insulating layer 13 on the n region 14. Further, an output amplifier 15 is connected to the floating @bj2 FD, and detects potential changes in the floating region FD.

The operation of this charge-coupled device will be explained with reference to Figures 4 and 5. α-position V added to transfer'bocal pole TGI and TG3
φH3 and the potential VφH2 applied to the transfer electrode TG2 are out of phase by 180'', and the signal charge is transferred by the two-phase purging method.The signal charge 7a transferred to the final stage transfer electrode TGI is at time 1. The potential generated by setting the transfer electrode TGI to a high level 5b is multiplied in the well 5.Next, by setting the transfer electrode TGI to a low level 5a at time t, the signal '!!, load 7a is applied to the output gate. OG exceeds the potential level 4a and is transferred to the floating area FD, but in order to empty the floating area FD before that, at time t.

From time t to time t, the reset gate R8 is set to high level 2b, and the already accumulated signal charge is discharged to the reset drain region RD. At this time, the output gate OG
On the contrary, set it to low level 4b. After the discharge of the signal '6, the reset gate R8 is returned to the low level 2a at time t4. The output game 1-OG is also returned to the high level 4a at the same time.

By operating in this manner, the floating region FD is dragged by a change in the potential of the adjacent reset gate IR8, but at the same time, it is also dragged by a change in the potential of the adjacent output gate OG. However, the direction of the potential change of the reset gate 1-R8 and the direction of the potential change of the output gate OG are
Since the direction of the change in the − position is opposite to the direction of the change, they are eventually canceled out, and no induced noise is generated in the floating region FD, and the output signal Vout shows only the change in the ′ and 6 positions due to the magnetic charge. Become.

In the previous embodiment, a two-phase one drive was used, but a multi-phase drive such as a three-phase one motion or a four-phase A'7A motion may be used.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain an output signal with a good S/N ratio without reset-induced noise simply by Q-rubbing the output gate so that it changes in phase opposite to that of the reset gate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the potential level of a conventional charge-coupled device, FIG. 2 is a time chart showing the operation of the same charge-coupled device, and FIG. 3 is a cross-sectional view of a charge-coupled device according to an embodiment of the present invention.
FIG. 4 is a diagram showing the potential level of the charge coupled device, and FIG. 5 is a time chart showing the operation of the charge coupled device. RD...Reset drain chain plate, R8...Reset gate, 1゛D...Float ink line area, OG...Output gate, TG, TGI, TG2. TG3...Transfer'
Hundred poles. Applicant's agent Kiyoshi Inomata (7) Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Scope of Claims] A plurality of transfer electrodes that transfer signal charges, an output gate adjacent to the final stage transfer electrode of the plurality of transfer electrodes, and an output gate that is in momentary contact with the output gate and whose potential exceeds the output gate. a floating accumulation region that accumulates incoming signal charges; a detection section that detects the signal charges accumulated in the floating accumulation region; In a charge-coupled device equipped with a reset gate voltage, the voltage applied to the output gate is synchronized with a change in the voltage applied to the reset gate. A charge-coupled device characterized by changing in the opposite direction.