Unit inverter having linearly varying delay response characteristic and digitally controlled oscillator including the unit inverter

摘要

A Digitally Controlled Oscillator (DCO) including a unit inverter cell whose output frequency linearly varies according to a digital control signal, the unit inverter cell linearly varying a delay response characteristic of an output signal with respect to an input signal supplied from an input terminal, in response to a reference signal and a zero^th control signal, and including a reference cell and a first selecting cell. The reference cell transmits the output signal to an output terminal, wherein the output signal is obtained by reversing a phase of the input signal in response to the reference signal and a reverse reference signal obtained by reversing a phase of the reference signal. The number of transistors forming the reference cell and the first selecting cell and sizes of the transistors are equal.