We have implemented a simple circuit of the rapid single‐flux‐quantum (RSFQ) logic family using a single‐layer YBa2Cu3O7−xthin‐film structure with 14 in‐plane Josephson junctions formed by direct electron beam writing. The circuit includes two dc/SFQ converters, two Josephson transmission lines, a complete RS SFQ flip‐flop, and an SFQ/dc converter (readout SQUID). Low‐frequency testing has shown that the dc‐current‐biased circuit operates correctly and reliably atT∼30 K, a few degrees below the effective critical temperature of the junctions. Prospects for a further increase of the operation temperature and implementation of more complex RSFQ circuits are discussed in brief. ©1995 American Institute of Physics.