Abstract
In recent years, portable devices such as media player, digital camera, smart phone, and tablet, are developed greatly. Non-volatile memories are used generally because these devices are not always turned on. Embedded non-volatile memories require a high voltage to attract electrons into the floating gate and an enough current to finish program operation in recent SoCs. Charge pump circuit is used in these chips to generate the high voltage. The supply voltage becomes lower and lower with more advanced process, but the high voltage can’t decrease because of endurance. Besides, the operating time is a very important specification for portable devices and using green power is the trend in future. Reducing supply voltage to 0.5V can fit these requirements. Traditional charge pumps can’t generate enough voltage and current and become slow and large at low supply voltage. In this work, we propose different structure and use hybrid devices with four-phase clock signals. The proposed circuit generates the first boosted voltage by clock pump and provides pumped clocks to main pump through level shifters. ALL blocks except main pump can use standard devices to reduce area because the first boosted voltage is only 1V. The low voltage charge pump was fabricated in UMC 90nm 1P9M process. It can meet the same specification at 0.5v supply voltage by measuring result. The structure can save about 15% area at the same voltage. Its speed at low voltage is almost equal to traditional pump at 1V. ALL of our goals are achieved.