Multiphase-Output Level Shift System used in Multiphase PLL for Low Power Application

Abstract

Low power design is essential for mobile application. For a PLL with multiphase outputs, level shifter (LS), which converts oscillator-output-level to that of power supply, consumes much power; hence, we have devised a new architecture called a multiphase-output level shift system (M-LSs) which has only three transistors in each LS and cuts off short current perfectly. Moreover, we have connected between the adjacent phases of M-LSs with a resistor to improve phase accuracy. The two key techniques mentioned above make power consumption 1/15 of the conventional LS. The PLL consumes about 1 mA at 123 MHz and accomplishes 63-phase accuracy of 0.5LSB.