An electrical test circuit is disclosed. In one embodiment, the electrical test circuit includes a first input for receiving a test signal of an integrated circuit, a second input for receiving a control signal and a third input for receiving a normalized reference signal, particularly one that is formed to be synchronous with the test signal. Using a control device of the electrical test circuit, the deviation and/or the amplitude and/or the phase of the reference signal and/or of the test signal can be varied. A measuring device generates, by subtracting the reference signal from the test signal, a difference signal which is output via an output.