A Quadrature Clock Corrector for DRAM Interfaces, With a Duty-Cycle and Quadrature Phase Detector Based on a Relaxation Oscillator

Abstract

A quadrature clock corrector uses relaxation oscillators to detect duty-cycle and quadrature phase errors by transforming them into pairs of frequencies, which are then digitized and compared. It achieves good detection accuracy and can detect a wide range of duty-cycle and quadrature phase errors. The prototype is implemented in a 55-nm CMOS process with a supply voltage of 1.2 V and occupies an area of 0.003 mm2. The experimental results show that the operation range is from 1 to 3 GHz, the power efficiency is 0.79 mW/GHz, the maximum duty-cycle error is 0.8% at 3 GHz, and the maximum quadrature phase error is 1.1° at 3 GHz.