A linear and compact charge-coupled charge packet differencer/replicator

Abstract

A new charge-coupled circuit for creating a charge packet equal to the difference of two input charge packets is analyzed. The circuit features inherent linearity through the use of quasi-three-dimensional charge-coupling, and can be implemented in a compact way. Depending upon the areal ratio of the circuit's primary electrodes, various fixed gains in the transfer characteristic may be obtained. The signal charges are transferred to the circuit through remote and possibly multiple floating diffusion collectors which may also function as summing nodes. Multiple copies of the output charge packet may be regenerated without refreshing the circuit input. A large geometry prototype device has been fabricated and characterized. The device demonstrates the operation of the circuit and features less than -40-dB linearity distortion over a dynamic range which exceeds 70 dB. Improved performance is expected in smaller geometry devices.