Patent ID: 8803535

Claim:
A comparison circuit for detecting impedance mismatch between pull-up and pull-down devices in a circuit to be monitored, the comparison circuit comprising: a comparator operative to receive first and second signals and to generate, as an output of the comparison circuit, a third signal indicative of a difference between the first and second signals; a first signal generator connected with a first input of the comparator and operative to generate the first signal indicative of a difference between reference pull-up and pull-down currents that is scaled by a prescribed amount, the reference pull-up current being indicative of a current flowing through at least one corresponding pull-up transistor device in the circuit to be monitored, the reference pull-down current being indicative of a current flowing through at least one corresponding pull-down transistor device in the circuit to be monitored; and a second signal generator connected with a second input of the comparator and operative to generate the second signal as a reference voltage defining a prescribed impedance mismatch threshold associated with the circuit to be monitored.