Design Of High-Performance DC-DC Converter In PMU

With the rapid development of semiconductor technology, the CMOS line width of has come to nanometer era. System on Chip becomes the first choice in the industry. In the consumer market, the boom of portable electronic products greatly improve the requirements of power supply chip, while large scale integration and high efficiency becomes the main trend. Therefore, to design power management unit with large scale integration and high performance becomes a necessary and meaningful task to industry.This thesis designs a high-performance DC-DC converter integrated in PMU. It proposes several techniques, such as voltage feed-forward circuit, full differential pseudo type-III compensation, due-mode control, auto-trim circuit to improve the key parameters of DC-DC converter, including line & load regulation, PSRR, efficiency, DVS recover time. Voltage forward circuit makes transfer function of system irrelevant to the input voltage, therefore improving line regulation performance. Full differential pseudo type-III compensation add a band-pass signal with a low-pass signal to achieve the type-III compensation with much less capacitor and resistor, meanwhile full differential configuration improves PSRR performance and suppress common mode noise and crosstalk from the ground. PWM/PSM due-mode control technique balance load regulation and efficiency, ensuring system’s load regulation under heavy load(PWM mode); while keeping high efficiency in light load(PSM mode). The auto-trim circuit modulate the duty ratio to ensure the output voltage within ±1% reference voltage, helping improve the load regulation performance and DVS recover time.The proposed converter’s switching frequency is 2MHz; its input voltage ranges from 2.7V to 4.2V; output voltage ranges from 0.7V to 1.5V with 25 mV step; the load current reaches 1A; Due to PSM/PWM due-mode control, under light load(PSM mode) efficiency reaches 80%, while in heavy load efficiency reaches 90%. Due to the full differential pseudo type-III compensation and auto-trim circuit, load regulation is within 1% under heavy load. Owning to voltage feed-forward circuit, line regulation is less than 1%. The PSRR of control circuits reach 116 dB within 1 kHz.