We present simple Complementary Josephson Junction circuits using 1kA/
cm(2) Nb junctions. We use long, sine-shaped junctions in order to ach
ieve gain and suppressed side lobes. We have simulated layout-extracte
d simple inverter and ring oscillator circuits to evaluate the perform
ance of these circuits in 1kA/cm(2) technology. Projected gate delays
with possible higher critical current density technologies are also si
mulated. We have experimentally tested the operation of inverter circu
its.