High-Efficiency Low-EMI Buck Converter Using Multistep PWL and PVT Insensitive Oscillator

This article presents a high-efficiency buck converter with electromagnetic interference (EMI) reduction. The proposed buck converter employs a simple method of piecewise linear (PWL) modulation to mitigate EMI significantly. Since EMI reduction tradesoff with efficiency and ripple content, this work also integrates the design of process, voltage, and temperature (PVT) insensitive crystal-less oscillator. This technique limits the modulated switching frequency to remain within range across all process corners, supply voltage. and operating temperatures, thereby limiting the range of efficiencies and ripple content that the buck converter will incur throughout its operation. As a result, the tradeoff between efficiency and ripple content is optimized while maintaining lower output voltage spurious noise tone. The chip was implemented using the 0.18 mu m 1p6m CMOS process. The measured results show that the power spectrum's peak noise is at -60.37 dBm, and the minimum efficiency is 93% with a ripple content of less than 43.7 mV for worst-case considering PVT variations at 2.2 V input, 1.7 V output with 100 mA load current.