Hier gibt es eine Beschreibung:
ASIC with Interpolator for Incremental Optical Encoders
A complete ASIC integrated the 10-fold interpolator and a phase-adjusting circuit was designed and fabricated in a 0.5 μm double-poly / double-metal CMOS process.

Vielleich hilft das schon.

https://pdfs.semanticscholar.org/7eee/e0a4ecb2ada3ba88451cc05b4317210cee3f.pdf