Title :
Digital Error Corrector for Phase Lead-Compensated Buck Converter in DVS Applications
Author :
Shaowei Zhen ; Xiaohui Zhu ; Ping Luo ; Yajuan He ; Bo Zhang
Author_Institution :
State Key Lab. of Electron. Thin Films & Integrated Devices, Chengdu, China
Abstract :
Modern low-power system on a chip needs direct current converter with dynamic voltage scaling (DVS) ability for core power supply. The converter output should be accurate voltage across the full load current and voltage scaling range. An integrated buck converter for DVS application is proposed in this brief. Voltage mode phase lead compensation is implemented in the converter, with much smaller passive components than conventional type-III compensation. To improve accuracy, the output voltage error accompanied with load current and reference voltage caused by finite loop gain in analog control loop is corrected by the digital error corrector. The output voltage is compared by two comparators whose threshold voltage is about 10 mV above and below the reference voltage, respectively. The duty cycle is slightly adjusted by finite state machine according to outputs of the two comparators. Experimental results show that the converter is well regulated over an output range of 0.7-1.8 V, with step voltage of 25 mV. When load current suddenly changes between 170 and 500 mA, the overshoot and undershoot voltage are 32 and 50 mV, respectively. Load regulation is maintained about 1% throughout the full load range. The voltage error is within ±10 mV in the voltage scaling range.
Keywords :
comparators (circuits); finite state machines; power convertors; DVS application; analog control loop; comparators; conventional type-III compensation; core power supply; digital error corrector; direct current converter; dynamic voltage scaling; finite loop gain; finite state machine; full load current; integrated buck converter; low-power system; output voltage error; passive component; phase lead-compensated buck converter; reference voltage; threshold voltage; voltage 0.7 V to 1.8 V; voltage 25 mV; voltage 32 mV; voltage 50 mV; voltage mode phase lead compensation; Bandwidth; Error correction; Radiation detectors; System-on-a-chip; Threshold voltage; Very large scale integration; Voltage control; Buck converter; digital error corrector; phase lead compensation; voltage mode control;
Journal_Title :
Very Large Scale Integration (VLSI) Systems, IEEE Transactions on
DOI :
10.1109/TVLSI.2012.2217513