PURPOSE: To improve yield by doubling in construction all capacitors concerned with Z-1 which is the parameter of the transfer function of a low-pass switched capacitor(SC) filter whose worst sensitivity goes to '0', and converting the parameter Z-1 into Z-2.

CONSTITUTION: The low-pass switched capacitor filter whose worst sensitivity to element deviation goes to '0' at a 0 frequency designed strictly based on a bilinear S-Z conversion is used. All the capacitors concerned with the Z-1 which is the parameter of the transfer function of this filter are doubled (CK1, CK2, CA11, CA31 and CA52) and the parameter Z-1 is converted into the Z-2. Thus, its central frequency is determined only by a clock frequency, is not influenced by the deviation of the values of the capacitors, therefore, the central frequency can be changed by changing the clock frequency simultaneously. By making the worst sensitivity of the low-pass SC filter at the '0' frequency to '0', the worst sensitivity at the central frequency goes to 0.