A low-power fast-lock DCC with a digital duty-cycle adjuster for LPDDR3 and LPDDR4 DRAMs

Abstract

A new low-power, fast-lock duty-cycle corrector (DCC) circuit with a digital duty-cycle adjuster (DCA) for mobile LPDDR3/LPDDR4 DRAMs is presented. The proposed DCC utilizes a digital feedback delay element (DFDE) to achieve wide duty-cycle correction and operating frequency ranges with low power consumption and fast lock capability. To obtain fast locking time and high duty-cycle correction accuracy, a 6-bit successive approximation register (SAR) controller utilizing a hybrid search algorithm is adopted. The measured duty-cycle error is less than ±0.85% over a 30–70% input duty-cycle range at 0.2–1.5 GHz. The DCC, which is fabricated in a 0.13-µm CMOS process, dissipates only 1.9 mW at 1 GHz and occupies an area of 0.036 mm².