An On-Chip Power Supply Regulator to Reduce the Switching Noise

In a synchronous clock-distribution network of typi cal automotive chips, digital circuits switch simultaneously on the clock edge; therefore, they generate high-switching (or di/dt) noise on the power supply lines due to sharp peaks of the supply cur rent, which is the source for electromagnetic emissions (EME). In this paper, we demonstrate an effective combination of two design techniques for di/dt noise reduction based on the supply current-shaping technique: 1) introducing an EME-suppressing regulator (EME-SR) with a digital feedback loop and 2) FM of the discrete-time EME-SR´s clock. The former technique reduces the time-domain peaks as well as the spectral power of the supply cur rent by a discrete-time EME-SR and a tank capacitor. The latter technique reduces the peak spectral power of the supply current by spreading this power into the sidelobes.