A novel analog mirror type DLL suitable for low voltage operation with self-calibration method

Abstract

introductionReduction of the power consumption is an important requirement in the case of high-speed memory in the batteryoperated system. The feedback type DLL[l] used in the high-speed interface increases the power dissipation due to the ceaseless and frequent feedback calibration. On the other hand, mirror type DLL is an attractive technology, which does not have a feedback loop and generates internal clock in two clock cycles by using two clock pulse intervals.Among mirror type DLLs. an analog typeI21, by virtue of its quantized-error-free-characteristics, is superior to the digital type [3.4]. However, precise operation of the architecture in Ref.2 is difficult. because matching between charging and discharging current sources is required. In particular, at low supply voltage, the applied voltage to the current sources, being only half of the supply voltage, results in the nonlinearity and mismatch of the sources.In this paper, we describe a new architecture of an analog mirror type DLL which can achieve precise operation at the supply voltage of 1.6V.