A complementary charge-sensing CCD filter using a single-gain-stage amplifier

THE CHARGE-TRANSFER split-electrode structure1,2 has two major limitations which result in inadequate performance in some applications. It requires two operational amplifiers to clamp the two sensing electrodes to a virtual reference voltage. A third amplifier is needed to obtain the differentials ignal. Improved approaches3y4 have been reported. However, a complex chargesensing circuitry is still required. A complementary chargesensing approach using charge-coupled device technology will be described in this paper. The approach only needs simple sensing circuitry, requires no contacts over gate-oxide and achieves a zero common-mode condition. Zero common-mode was reportedly achieved5 but a bucket-brigade was used and contact over gate-oxide was needed.