A Low-EMI Buck Converter Suitable for Wireless Sensor Networks With Spur-Reduction Techniques

This paper presents a low electromagnetic interference buck converter for wireless sensor networks with the spur-reduction techniques. The proposed buck converter uses the third-order delta-sigma modulator (DSM) with its noise-shaping characteristic to achieve low output noise. The DSM is designed with the chopper-stabilization techniques, which further reduces the impacts of low-frequency noises, such as flicker noise and offset voltage. The proposed buck converter also adopts fast transient path in order to get a fast transient response. The proposed buck converter has been fabricated with a TSMC 0.35-μm CMOS 2P4M process. The area of the whole chip is 2.18 mm
²
. Compared with previous works, the noise floor of the proposed converter's output is below -76 dBm, which is lower than others. The settling time of the proposed converter's output is ~20 μs with the load current skipping between 50 and 500 mA, that is faster than previous works, too. Moreover, the peak efficiency of the proposed converter is better and equals to 90%.