Filter circuit with closed loop - has charge transfer lines and specified coupling-out points leading to differential amplifier

摘要

The filter circuit has at least one resonator in the form of a closed unidirectional loop. An input charge-transfer line (1) and an outpur charge-transfer line (2) are connected to the loop. The capacitance of the loop differs from that of the two CTD lines. The closed loop has coupling-out points at those places where the signal charge at the loop resonant frequency has a phase shift of 180 degrees. The signals coupled out at these places are combined in a differential amplifier (V). Alternatively, if two loops are present then the coupled-out signals are passed to the input of the second loop. The couoling-out is accomplished using floating gates (FG).