A cost-effective filter consuming low power and occupying minimal space.
The filter may be used in a ADSL modem (or CPE) to filter the signal
components other than the ADSL signals. A high pass filter first filters
the low frequency components to attenuate (or remove) lower frequency
components such as that caused by ADSL transmit echo signals and that used
for voice transmission. The high pass filter may be modified by adding a
few resistors to limit the voltages of the high frequency signals also.
The output of the high pass filter is amplified and passed through a low
pass filter to filter the high frequency components (HPNA included). Due
to earlier filtering operation of the high pass filter, the signal can be
amplified substantially before being sent to the low pass filter. The
implementation of the low pass filter is simplified due to the prior
amplification.
