Development of Pulse Transfer Circuits for Serially Biased SFQ Circuits Using the Nb 9-Layer 1-$\mu\hbox{m}$ Process

Serial biasing is a promising technology to reduce the total bias current of single flux quantum (SFQ) circuits. In this technique, each circuit block is placed on separated floating ground planes and biased serially. In this study, we developed a new coupling structure of SFQ pulse transfer circuits between the different ground planes using the Nb 9-layer ISTEC advanced process (ADP2.3). By using thick insulating and shielding layers, the pulse transfer circuit became robust to external magnetic fields with enough bias margins. The high-speed operation of serially biased SFQ circuits was demonstrated by on-chip high-speed tests.