Semiconductor integrated circuit
AssigneeSanyo Electric Co., Ltd.
InventorTomoki Shioda
Life of this patent
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Abstract
A coupling capacitor for converting the DC level between circuits is incorporated into a semiconductor integrated circuit to reduce the number components. A high-pass filter (34) having a cutoff frequency fC is composed of a coupling capacitor C1 that cuts off direct current between circuits (22) and (24), and a switched capacitor circuit (28) constituting an equivalent resistor RSC. If the switching frequency fSC or the capacitance CSC charged and discharged by the switched capacitor circuit (28) is set low, the RSC can be increased and the C1 at the prescribed fC can be reduced proportionately. Accordingly, the high-pass filter (34) having the C1 can be integrated onto the chip of the IC (20).
Claims4
A semiconductor integrated circuit in which a high-pass filter is formed on a shared semiconductor substrate, said high-pass filter comprising:
- a coupling capacitor which is inserted in series in a signal pathway for transmitting signals and which capacitively couples output side and input side of said signal pathway;
- and
- a switched capacitor circuit that functions as an equivalent resistive element between a prescribed reference DC voltage source and a terminal of said coupling capacitor connected to said output side of said signal pathway.
Dependencies are inferred from the claim text.