A Method to Reduce the Effect of the Switching Noise in Analog-Mixed Circuits

Sample-hold is one of the basic non-linear functions in analog-mixed circuits. Switching noise can critically affect the operation for such a function, particularly in case of current sample-hold, if no effective measures are taken to reduce it. In this paper, a method for an efficient reduction of the effect of the switching noise is proposed. The principle of this method is to bias a transistor in the operation region where it has a weak transconductance and an attenuating voltage transfer characteristic, and use this device to absorb the switching noise, in order to protect the critical circuit nodes. This method can be implemented very easily without need of any devices requiring linearity or precision. A current memory cell is designed with this method and the simulation results show that the switching noise causes much less negative effect to the circuit operation.