A New Low-Noise I-Squared Buck Converter Suitable for Wireless Sensor Networks With Dual-Current-Acceleration Techniques

Abstract

This paper proposed a new low-noise I-squard $2^{nd}$ -order continuous-time-delta-sigma-modulation (CT-DSM) buck converter suitable for wireless sensor networks with dual-current-acceleration (DCA) techniques. First, it adopts the second-order CT-DSM scheme, which can effectively utilize the oversampling and the noise shaping techniques to disperse the noise and push it to higher frequencies. Second, the use of the pseudo-inductor-current-sensor can increase the bandwidth of the closed-loop gain and consequently speeds up the transient response of the converter. Third, the dynamic-current regulator utilizes the principle of current charging and discharging to make the converter respond faster when the load changes dynamically. Fourth, this paper combines the pseudo-inductor-current-sensor and the dynamic-current regulator to realize the dual-current-acceleration technique, which can accelerate the transient response by up to 45.5%. The proposed converter is designed and fabricated in TSMC $0.18\mu \text{m}$ 1P6M CMOS process, and the chip area is 1.065 mm2. When the load current changes from 50mA to 500mA and 500mA to 50mA, the transient responses are $2.4\mu \text{s}$ and $3\mu \text{s}$ , respectively, and the peak efficiency is 92.4%. The measurement result of ONR is 78.087dB, with the sampling frequency of 10 MHz.

Keywords

• Fast-transient
• second-order delta-sigma modulation
• dual-current-acceleration technique
• pseudo-DCR current-sensor
• buck converter