Patent ID: 8164380
Filing Date: 2012-04-24
Classification: H03D,H03H

Abstract:
1. A discrete filter comprising: a control signal generation section that generates N control signals having the same frequency and having phases which are each shifted by a 1/N period (where N is three or four); a history capacitor coupled to an input for receiving sampled signals that performs temporally continuous integration of the sampled signals; a switched capacitor section coupled to the input that comprises N switched capacitor circuits connected in parallel to each other, each switched capacitor circuit having a rotation capacitor to repeat integrating the sampled signals integrated in the history capacitor and discharging the integrated sampled signals; and a buffer capacitor coupled to said switched capacitor section that buffers the integrated sampled signals discharged by the rotation capacitors of the N switched capacitor circuits, wherein: each switched capacitor circuit has an integration switch to switch a state of input to the rotation capacitor and a discharge switch to switch a state of discharge from the rotation capacitor; the control signal generation section outputs a control signal of the N control signals to each of the respective integration switches and discharge switches of the N switched capacitor circuits; and each switched capacitor circuit repeats, in the rotation capacitor, at least two operations of an integration operation of the sampled signals integrated in the history capacitor and a discharge operation of the sampled signals to the buffer capacitor in accordance with the control signals, and at each instant of time one of the switched capacitor circuits is performing one of the two operations, the other switched capacitor circuits do not perform the same operation as the one of the two operations.