An integrated circuit includes a first circuit and a test circuit. The test circuit is configured to test the timing of a first circuit. The first circuit includes a plurality of flip-flops and a plurality of data paths. Each data path of the plurality of data paths is connected to one or more of the plurality of flip-flops. The test circuit includes a plurality of loopback paths, a controller, a multiplexer connected to the plurality of loopback paths and a counter connected to the multiplexer. The controller is configured to select a path from the plurality of loopback paths and the plurality of data paths. The multiplexer is configured to selectively output a first signal including an oscillation frequency. The first signal is applied to the selected path and the counter is configured to measure the oscillation frequency of the first signal.