Charge coupled device with controllable input bias.

摘要

In a charge-coupled device, a DC bias on its signal register (12) input is automatically corrected for thermal fluctuations and other environmental effects. First and second reference registers (14, 16) are deposited on the same substrate (10) as the signal register (12). The first reference register (14) has the same input structure and control as the signal register (12) and the same output end as the second reference register (16). The input channel width of the second register (16) is selected such that the ratio of the input widths (a) of the first and second reference registers (14, 16) matches the ratio of the dynamic range and desired bias level of the signal register. All three registers are clocked synchronously, but the input of the second register is charge saturated while the other registers are biased to the same degree. The output charges of the two reference registers (14, 16) are compared and their difference is fed back to the inputs to the signal register and first reference register to adjust the bias level.