| dc.description.abstract | In recent years, the portable electronic products must integrate a wide range of functions to obtain the favor of consumers, so in order to extend the battery life time, the system will switch to different mode according to the usage of the product, and also need good efficiency. Therefore, the power management IC should have fast transient response to provide the loading current, because copes with such frequent and rapid mode switching. Furthermore, the conventional voltage or current mode because the loop compensation resulting in bandwidth is narrow, its slow transient response. This thesis will use the hysteretic voltage-mode control of buck converter which has a fast transient response and simple structure.
However, due to the propagation delay the output voltage cannot oscillate the pre-defined hysteresis window, also cause the output voltage ripple larger. Therefore, the thesis proposes an adaptive ripple controller to improve this problem. And during the start-up period, the inductor current will raise beyond the current limit of the power switches for a short time; we use the method of selecting two P-type power switches.
The conventional hysteretic voltage-mode control of buck converter is implemented with TSMC 0.35um (5V) CMOS process. In the proposed buck converter, the input voltage is 3.4V ~5V, the output voltage is 0.7V~2.5V, the loading current is from 50mA ~600mA, and the highest efficiency is 92.7%. This circuit with adaptive ripple controller can generate a virtual window for hysteretic comparator such that the sawtooth signal of output voltage is controlled to be within the given window, when the input voltage is 5V, output voltage is 1V or 2.5V and the pre-defined window is 20mV for example.
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