Phase locked loop and semiconductor device using the same
First Claim
1. A phase locked loop comprising a voltage controlled oscillator and a loop filter including a transistor and a capacitor electrically connected to the transistor,wherein a channel formation region of the transistor comprises an oxide semiconductor material,wherein the capacitor is configured to hold a potential when the transistor is off,wherein the potential is input to the loop filter, andwherein the transistor is configured to be turned off when a cycle of a periodic signal output from the voltage controlled oscillator is constant.
1 Assignment
0 Petitions
Accused Products
Abstract
It is an object of the present invention to provide a phase locked loop in which a voltage signal input to a voltage controlled oscillator after a return from a stand-by state becomes constant in a short time and power consumption is reduced. A transistor including a semiconductor layer formed using an oxide semiconductor material is provided between an input terminal of a voltage controlled oscillator and a capacitor of a loop filter. The transistor is turned on in a normal operation state and turned off in a stand-by state.
117 Citations
21 Claims
-
1. A phase locked loop comprising a voltage controlled oscillator and a loop filter including a transistor and a capacitor electrically connected to the transistor,
wherein a channel formation region of the transistor comprises an oxide semiconductor material, wherein the capacitor is configured to hold a potential when the transistor is off, wherein the potential is input to the loop filter, and wherein the transistor is configured to be turned off when a cycle of a periodic signal output from the voltage controlled oscillator is constant.
-
7. A semiconductor device comprising a phase locked loop including a voltage controlled oscillator and a loop filter comprising a transistor and a capacitor electrically connected to the transistor,
wherein a channel formation region of the transistor comprises an oxide semiconductor material, wherein the phase locked loop is configured to become a stand-by state after the transistor is turned off, wherein the phase locked loop is configured to be returned from the stand-by state after the transistor is turned on, and wherein the transistor is configured to be turned off when a cycle of a periodic signal output from the voltage controlled oscillator is constant.
-
12. A semiconductor device comprising a phase locked loop including:
-
a phase frequency detector configured to receive a first periodic signal and a second periodic signal and configured to output a third periodic signal corresponding to a phase difference between the first periodic signal and the second periodic signal; a charge pump configured to receive the third periodic signal and configured to output a first analog signal corresponding to the third periodic signal; a loop filter configured to receive the first analog signal and configured to output a second analog signal corresponding to the first analog signal; and a voltage controlled oscillator configured to receive the second analog signal and configured to output a fourth periodic signal corresponding to the second analog signal, wherein the loop filter comprises a transistor and a capacitor, wherein a channel formation region of the transistor comprises an oxide semiconductor material, wherein one of a source electrode and a drain electrode of the transistor is electrically connected to the charge pump and the voltage controlled oscillator, wherein the other of the source electrode and the drain electrode of the transistor is electrically connected to the capacitor, wherein the phase locked loop is configured to become a stand-by state after the transistor is turned off, wherein the phase locked loop is configured to be returned from the stand-by state after the transistor is turned on, and wherein the transistor is configured to be turned off when a cycle of the fourth periodic signal is constant. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
-
Specification