All Digital and High Precision DC-DC Converter with Negative Current Reduction

Since the continuous progressing for the integrated circuit process, the portable devices of the future, such as mobile phone, personal digital assistant, digital camera, and notebook computer, etc. The supply voltage needed is getting lower and lower, and the using time needed is getting more and more. A 90nm process for example, the supply voltage is down to 1V, which gives rise to some serious problems like the background noise, process and temperature parameters variation, and submicron effects such as sub‐threshold current leakage, drain‐induced barrier lowing, and parasitic capacitance, etc. all of the above problems lead to much more complexity for designers. Similarly, the analog signal suffers the parameters variation and the lower signal‐to‐noise ratio, which obviously reduce the reliability. Hence, the high frequency, low power consumption, and low supply voltage of the digital control techniques are very attractive to designers. However, in spite of the progressing of the process and the supply voltage had downed to 1V, the batteries in the market still provide more the 3V in general. For example, the mobile phone and digital camera use 3.6V battery, the wireless mouse and keyboard use the multiple of 1.5V (for a dry battery), and the USB port of computer supply 5V, etc. all the above devices supply larger voltage than which the chips need. So we have to design the circuits between the chip and the power supply. That is why the dc‐dc converter so important, especially when the devices operate in standby mode with quiescent current or in functional mode with heavy throughput. Hence, the more powerful functionality and the more using time the portable equipments have, the better quality and larger value they have. This project intend to realize the converter with digital control loop, so that it can achieves lower sensitivity to process and temperature variation, easy to integrated, possible for transforming to other systems, and even can it reduce or eliminate the passive components of the control loop. These can be the most important characteristics of the digitally controlled dc‐dc converter.

Project ID:PB9808-2405
External Project ID:NSC98-2221-E182-049