| 摘要 |
<p>Switched-capacitor circuit (50) for passing an audio frequency over a predetermined range of frequencies fabricated on a monolithic semiconductor substrate. The switched-capacitor filter (50) includes a first amplifier (60) and a second amplifier (90). A first integrator capacitor (66) is interconnected to the first amplifier (60). A second integrator capacitor (96) is interconnected to the first amplifier (90). A first input switched-capacitor (82) is interconnected between the first amplifier (60) and the second amplifier (90), such that the first input switched-capacitor (82) samples and holds the output of the second amplifier (90) during a first clock phase thereby isolating the output of the second amplifier (90) from the input of the first amplifier (60). During a second clock phase the first input switched-capacitor (82) applies the output of the second amplifier (90) to the first integrator capacitor (66). A second input switched-capacitor (112) is provided and is interconnected between the output of the first amplifier (60) and the input of the second amplifier (90), such that during the second clock phase the second input switched-capacitor (112) applies the output of the first amplifier (60) to the second integrator capacitor (96). The switched-capacitor circuit (50) functions such that effectively zero phase shift is introduced into the signal being processed by the switched-capacitor circuit (50). </p> |
