A low voltage logic circuit with asynchronous SET and/or RESET functions
is described herein. The low voltage logic circuit may be primarily used
in forming low voltage flip-flop circuits, but may also be used to form
multiplexers and other logic configurations. The flip-flop circuit
described herein improves upon existing low voltage architectures by
providing a flip-flop circuit, which can operate at relatively low supply
voltages (e.g., less than about 1.8V), with SET and/or RESET capability.
In doing so, the improved flip-flop circuit may be used within a phase
frequency detector, programmable counter, or frequency divider of a phase
locked loop (PLL) or delay locked loop (DLL) device. However, the
improved flip-flop circuit may be used with any low voltage circuit or
device that may require, use or benefit from a SET or RESET function. In
some embodiments, one or more level shift circuits may be included so
that the low voltage flip-flop circuit may receive CML, TTL and/or CMOS
logic levels (among others).