Design of a Low EMI Synchronous Dual-Mode Boost Regulator

• Main Authors: Tseng, Chun-Chang, 曾俊昌
• Other Authors: 劉萬榮
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/22325280696600690118

碩士 === 國立臺北大學 === 電機工程研究所 === 98 === Portable electronic devices nowadays require much higher clock frequency and signal speed. With an increase in the clock frequency, there is also a serious rise in the electromagnetic interference (EMI) in these devices. Hence, portable electronic products these days are equipped with the required countermeasures to reduce the EMI problem. This research focuses on the EMI problems produced in switching boost regulators. This work utilizes the spread-spectrum technology to decentralize or spread the peak energy spectrum of the clock signal viewed in the frequency domain. This reduces the EMI considerably as has been shown in this work. The EMI reduces by about 10 ~ 20 dB. The spread-spectrum circuit is a simple and effective circuit. It can be easily implemented on the chip. The circuit also consumes less power and area. The dual-mode boost regulator circuit designed here selects the mode of operation using a multiplexer depending on the size of the load. This gives rise to a high efficiency for the circuit. Also, this circuit uses a synchronous architecture which gives rise to high conversion efficiency and helps in including the power switching elements on-chip. This reduces the area of the chip considerably, allowing this circuit to be used in thin, light weight portable products. The TSMC 0.35-µm 2P4M CMOS process was used for this design. The input voltage range for the circuit is 2.7V to 4.2V and the required output voltage for the circuit is 5V. When the circuit is operating in the pulse width modulation mode, the output voltage ripple obtained is 15mV. When the circuit is operating in the pulse frequency modulation mode, the output voltage ripple is 58mV. The area of the chip is 2.3 × 2.3 mm2, and the highest conversion efficiency of the regulator obtained is 96.7%.