| 摘要 |
A circuit (15) for detecting, with minimum offset, the zero crossing of the alternating analog output voltage of a switched-condenser filter (3). The circuit (15) comprises a smoothing filter (20) connected to the output of the switched-condenser filter (3) and generating a smoothed alternating signal; a low-pass filter (21), also connected to the output of the switched-condenser filter (3), for detecting the direct-current offset of the alternating signal; and a comparator (12), input connected to the smoothing filter (20) and the low-pass filter (21), for comparing the smoothed alternating signal with the direct-current offset, and so determining the zero-crossing of the smoothed alternating signal (sinusoid). <IMAGE> |
