Low Power Design For CPU Of Baseband Chip

Various kinds of portable electronic products on the market at present are more and more popular, especially with the smartphones. With the enrichment of the functions of smartphones, the power consumption of smartphones is increasing rapidly. But the smartphones and other electronic products still depend on the battery power, to improve the experience of consumers, it would be better to extend the battery life with the certain power. Thus how to reduce the power consumption of the smartphones and other electronic products becomes a research focus in the industry at present. Baseband chip is the most important chip in the smartphones, and it is responsible for communication. The current mainstream baseband chip can support 2G, 3G and 4G network systems, and it is integrated with tens of millions gates. The CPU in the baseband chip is the core of system operation and control center, and it is used for processing instructions and data. Being the most active part of the chip, the CPU is processing more and more tasks with the enrichment of the functions of the baseband chip. Thus the power consumption of the CPU is very high. Reducing the CPU power consumption is helpful to reduce the power consumption of the whole chip. In the meantime, reducing the CPU power consumption can promote the development of the smartphones. Based on this background, this thesis designs the CPU of the baseband chip with low power consumption.The main work of this thesis is low power consumption design of the CPU of an ARM kernel based baseband chip, using technology of dynamic voltage frequency scaling, including two units: the CPU profiling unit and the voltage scaling control unit. The main idea of the design is that adjusting the voltage and the frequency dynamically to save power when the CPU processing task is not heavy.The CPU profiling unit is mainly used to measure the CPU load by calculating the proportion of the active CPU cycles within each monitoring period. Then it sets the CPU performance level request signal to the voltage scaling control unit according to the load condition of the CPU. This unit includes four modules: Time tracking, Averaging, Threshold checking and Performance tracking.The voltage scaling control unit is mainly used to scaling the voltage and the frequency of the VDD_CORE power domain which includes the CPU. This unit processes the performance level request of the CPU and then sets a select signal to the power management unit which provides the required voltage. In addition, it sets frequency request signals of the modules in the VDD_CORE power domain to the clock generation unit which generates the clocks. This unit ensures that the voltage and frequency change requests of each module cab be responded correctly by the system. And then the system provides the required voltages and frequencies.This thesis verifies the two units respectively. The simulation results reveal that the functions of the two units are achieved correctly. The test data after baseband chip taped out shows that the whole chip power consumption reduced nearly 60%. It approves that the two units have achieved the dynamic scaling of voltage and frequency for the CPU, reducing the power consumption of the CPU. The two units have important significance for the low power consumption of the whole baseband chip.