HIGH-ORDER SWITCHED CAPACITOR FILTER WITH DIGITAL-TO-ANALOG CONVERTER AT INPUT

摘要

PURPOSE: To provide the high-order switched capacitor filter which filters a 1-bit digital signal flow with low noise. ;CONSTITUTION: The digital-to-analog converter(DAC) has a delta-sigma modulator 10 which converts a digital input to a 1-bit digital output and a quadratic switched capacitor filter 12 which converts the 1-bit digital output into an analog value in a sample data area. This analog value after being inputted to a switched capacitor/continuance buffer 14 is filtered by an active low-pass filter 18 into an analog output. The output of the 1-bit DAC 20 is added to the output 26 of an integration means 38 as a 4th stage at addition points 22 and 42. Thus, an integration means 24 as a 1st stage operates on the noise output of the 4th integration stage to reduce it, thereby actualizing the high-order switched capacitor filter with low noise.;COPYRIGHT: (C)1993,JPO