| 摘要 |
An ADSL receiver HPF architecture 300 that reduces the number of Op Amps below that required for known ADSL receiver HPFs. The ADSL receiver HPF 300 is implemented as an active RC filter to provide a single fifth-order Elliptic filter instead of the more conventional pair of third-order Elliptic filters. Since the HPF Elliptic filter stage having the lowest Q factor is reduced as the order of an Elliptic filter transfer function is increased, a single fifth-order Elliptic filter suitable for use as an ADSL receiver HPF can be implemented using only one Op Amp in the second 2<nd>-order HPF stage 308. A notch (imaginary zero) is provided by summing of output signals associated with active RC structure state variables. This structure minimizes the number of capacitors while preserving the capability to provide a high Q factor for the first 2<nd>-order HPF stage 304.
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