In system-on-chip applications, the digital switching noise propagates through substrate and power distribution to analog circuits, degrading their performance. To monitor and analyze the digital switching noise coupling, small and compact sensors that can be embedded within high-density circuits are essential. This paper presents PMOS-based differential substrate and power-supply sensors and an on-chip waveform sampler, which focus on wide bandwidth, reduced parasitic interactions, and small compact size. The bandwidth of the proposed sensors, which is implemented with an IBM 0.13- CMOS technology, is useful from DC to 1.6 GHz. Linearity is better than 1.5% for substrate and 6% for power-supply sensors. Power-supply rejection of 64 dB has been achieved in the substrate probing. The substrate noise coupling into the power-supply probing was below detectable limits. Experimentally reconstructed waveforms with 20-ps time resolution allowed the measurement of amplitude, rise time, and overshoot of transition edges.