A circuit for a data processing apparatus and a method for detecting
spurious signals is disclosed, the circuit comprising a data input
operable to receive digital signal values, spurious signal detection
logic operable to monitor a digital signal value within the circuit, and
to determine at least one of: a safe time window during which it is
expected that the digital signal values input into the circuit may cause
data transitions in the monitored digital signal value and a transition
time window in which it is expected a data transition will occur; and in
response to detecting either a data transition in the monitored digital
signal value outside of the at least one safe time window or no data
transition in the transition window, the spurious signal detection logic
is operable to output a detection signal.