We found this circuit in the October 1994 issue of Electronics Now magazine. The circuit uses a now-uncommon 4046 PLL and the gates of a CMOS 4001.
The circuit presented in the figure is an amplifier for stereo sources with the Maxim MAX9723...
This circuit has been found in an old American documentation, but can be easily implemented with common...
The integrated circuit used in this filter is not very common today, but the reader can use...