We have fabricated a GaAs diode sampling head which has a bandwidth of 130 GHz, which is a five times improvement over previous room‐temperature designs. This speed is attained with a monolithic sampling head design integrated with two nonlinear transmission lines which serve as the strobe pulse and test signal generators. A 4 ps transition time has been measured with the sampler. We have also measured sinusoidal waveforms to 120 GHz.