  Recent progress of Reciprocal Quantum Logic (RQL) has renewed interest in AC
powering of superconductor digital circuits, which had been abandoned since the
famous IBM project of 1970s. In this work we propose and demonstrate new
AC-biased Single Flux Quantum (SFQ) circuits, and search for synergy of AC and
currently dominating DC biasing schemes. As the first step, we suggest an
on-chip AC/DC converter capable of feeding a few DC-biased gates surrounded by
their AC-biased counterparts. As the second step, we introduce and present the
first successful demonstration of a new AC-powered circuit - an 8192-bit shift
register with over 32,800 Josephson junctions (JJs) and JJ density of about
6x$10^5$ JJ per $cm^2$. We suggest a few niche applications for this type of
AC-biased circuits, not requiring high clock rates. E.g., these, scalable to
millions of JJs per chip, circuits can serve as a convenient benchmark for new
SFQ fabrication technology nodes, allowing the operating margins of individual
cells to be extracted and, thus, 'visualize' individual fabrication defects and
flux trapping events. The circuit can also be developed into a mega-pixel
imaging array for a magnetic field microscope.
