i have read in my text book that : " A flip-flop is the simplest synchronous sequential circuit. "
but it is not convincing at all since we cannot analyze or build a flip flop like a synchronous circuit .
even i asked a question about how to design a flip flop with having it's truth table .
and the person who answered (Francesco Conti) claimed that flip flops are asynchronous circuits ?
what type are flip flops ?
EDIT by flip flop i mean an edge triggered D flip flop .
the best definition i could find of synchronous and asynchronous circuits is here: http://www.ee.usyd.edu.au/tutorials/digital_tutorial/part3/sa-op.htm
it states that :
Synchronous sequential circuits change their states and output values at discrete instants of time, which are specified by the rising and falling edge of a free-running clock signal
In asynchronous sequential circuits, the transition from one state to another is initiated by the change in the primary inputs; there is no external synchronization.
After Reading the proper answer i think we can say that :
if you look at a D-flipflop as a whole it's function IS synchronous
BUT since it's the building block of synchronous circuits obviously it's not possible to design it like a synchronous circuit (since then we would use FlipFlops to design FlipFlops) so it's design is like asynchronous circuits and has no algorithm.
to sum it up since the flip flops are the elements that make the transition from asynchronous to synchronous possible ; (in other words they are the building blocks of the synchronous circuits ) then they are some where between synchronous and asynchronous circuits .
their design is asynchronous since they are the first synchronous circuit to be made.(so they must emerge from asynchronous circuits and asynchronous design)
while their function is synchronous .(they change their states and output values at discrete instants of time)