A circuit in a semiconductor device for testing jitter tolerance of a receiver in the semiconductor device. The circuit includes a jitter injection circuit that has an output connected to an input in a phase-locked loop circuit. The jitter injection circuit generates an output signal in response to an application of an input signal. The phase-locked loop circuit has an output that generates a clock signal, wherein the clock signal may be altered by the output signal from the jitter injection circuit. The clock signal from the phase-locked loop circuit controls transmission of data at the transmitter. Alteration of the clock signal caused by the jitter injection circuit alters the manner in which the transmitter transmits data.