A Fast Locking Duty Cycle Corrector with High Accuracy

This paper presents a fast locking duty cycle corrector (DCC) with high accuracy for mobile memory. The DCC has a low pass filter to convert detected values by duty cycle detector (DCD) into offset voltages and transmit the voltages to duty cycle adjuster (DCA) to adjust common mode voltages. The low pass filter has a tradeoff between correction time and accuracy depending on the capacitor value. The dual loop low pass filter (DLLPF) has been proposed for high accuracy and fast correction time. The locking time is 1.89 times faster and the fluctuation is 9.21 times lower compared to conventional low pass filter. The circuit is implemented in CMOS 0.18-µm technology using 1.8-V supply. The output duty cycle is corrected to 50±1% over the input duty cycle range of 20-80% for 1.6GHz.