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This paper presents a high-efficient low-noise buck converter with continuous-time delta-sigma-modulation and burst-mode techniques. The proposed buck converter uses the techniques of over-sampling, noise shaping, burst mode, and continuous-time second-order delta-sigma modulator to achieve low output noise, low overshoot and undershoot voltage, and improve the recovery time. First, the second-order DSM can lower the switching frequency noise, overshoot, and undershoot of the converter. Second, the noise shaping technique can move the noise to high frequency and filter out the noise within bandwidth. Third, the burst-mode technique can accelerate the transient response. The proposed chip is fabricated with a 0.35 μ m Taiwan Semiconductor Manufacturing Company (TSMC) CMOS process and the chip area is 1.5 × 1.5 mm. The transient recovery time is 6 and 16 μ s, when the load current changes from 600 to 50 mA and from 50 to 600 mA, respectively. The output noise spectrum is –67.5 dbm, when output voltage is 2 V. The maximum efficiency is 91.6%, when the output voltage is 2 V. The supply voltage is 3.3 V. The output voltage range of the proposed converter is 1–2.5 V.

A new current-mode buck converter with current sensing and pulse width modulation (PWM) techniques is proposed. The improved-I2 controlled buck converter achieved a fast transient response and a wider bandwidth. The presented circuit with sensing control can reduce the number of the components. The buck converter provided the current load range within 50mA∼700mA. It has low output voltages and current ripples. The buck converter has been designed and implemented with TSMC 0.35μm CMOS 2P4M technology. The maximum power efficiency is 90.8%. The area of the whole chip is 1.5mm × 1.5mm.

This paper presents a multiphase buck converter with optimum-damping-control and current-balanced techniques. The proposed optimum-damping-control and current-balanced techniques can achieve current balance to avoid output current flow in one phase. The phase controller is used to control multiphase buck converter. This configuration provides wide output current range from 400 mA to 4 A. It also has low output voltage and current ripple. The proposed buck converter has been fabricated in TSMC 0.35µm CMOS 2P4M technology, and the areas of the chips are 1.896 mm × 1.852 mm and 1.339 mm × 1.439 mm. The power efficiency can be up to 89.5%.