Adaptive cancellation of fixed-pattern noise in c.c.d. serial-parallel-serial memory

The letter addresses the problem of the effective implementation of long analogue delay lines. Charge-coupled devices (c.c.d.) appear attractive for this application but suffer from the problem of signal smearing due to imperfect charge transfer. Although s.p.s. delay-line configurations minimise charge-transfer inefficiency, they emphasise the significance of dark current which can cause severe fixed-pattern noise problems in this architecture. A scheme is proposed here for the cancellation of fixed-pattern noise in s.p.s. delay lines and results are presented to demonstrate the effectiveness of the system.