Voltage controlled oscillator including fluctuation transmitter for transmitting potential fluctuation by noise

A voltage controlled oscillator comprising:

• an oscillation controller configured to generate first and second control potentials corresponding to an input voltage;
• first and second current sources configured to generate control currents corresponding to said first and second control potentials, respectively;
• an oscillation section, connected to a power source potential node via said first current source and connected to a ground potential node via said second current source, said oscillation section generating a clock whose oscillation frequency is determined by said control current, said oscillation section including a delay circuits each having first and second inverter circuits each having a power source terminal and a ground terminal, in which said first and second inverter circuits output reverse signals of input signals after a delay time corresponding to said control currents generated by said first and second current sources, said first current source is disposed between the power source terminals of said first and second inverter circuits and said power source potential node, and said second current source is disposed between the ground terminals of the first and second inverter circuits and said ground potential node;
• an amplitude upper/lower limit circuit configured to determine an upper limit and a lower limit of a potential of an output node of said first and second inverter circuits;
• and
• an amplitude control circuit configured to control an upper limit value and a lower limit value of the potential of the output node of said first and second inverter circuits limited by said amplitude upper/lower limit circuit.

A delay circuit comprising:

• first and second inverter circuits each having a power source terminal and a ground terminal, said first and second inverter circuits outputting a reverse signal of an input signal after a delay time;
• a first current source, disposed between the power source terminals of said first and second inverter circuits and a power source potential node, said first current source generating a first control current, which determines said delay time, based on a first control potential applied from the outside and preventing a noise superimposed on said power source potential node from being mixed into said power source terminal;
• a second current source, disposed between the ground terminals of said first and second inverter circuits and a ground potential node, said second current source generating a second control current, which determines said delay time together with said first control current, based on a second control potential applied from the outside and preventing a noise superimposed on said ground potential node from being mixed into said ground terminal;
• a first fluctuation transmitter, disposed between said power source potential node and said first control potential node, said first fluctuation transmitter transmitting a potential fluctuation generated in said power source potential node to said first control potential node at the same phase and maintaining a potential difference between the power source potential and the first control potential to be constant;
• and
• a second fluctuation transmitter, disposed between said ground potential node and said second control potential node, said second fluctuation transmitter transmitting the potential fluctuation generated in said ground potential node to said second control potential node at the same phase and maintaining the potential difference between the ground potential and the second control potential to be constant.

A delay circuit comprising:

• first and second inverter circuits each having a power source terminal and a ground terminal, said first and second inverter circuits outputting a reverse signal of an input signal after a delay time;
• a first current source, disposed between the power source terminals of said first and second inverter circuits and a power source potential node, said first current source generating a first control current, which determines said delay time, based on a first control potential applied from the outside and preventing a noise superimposed on said power source potential node from being mixed into said power source terminal;
• a second current source, disposed between the ground terminals of said first and second inverter circuits and a ground potential node, said second current source generating a second control current, which determines said delay time together with said first control current, based on a second control potential applied from the outside and preventing a noise superimposed on said ground potential node from being mixed into said ground terminal;
• an upper/lower limit circuit configured to determine an upper limit and a lower limit of a potential of an output node of said first and second inverter circuits;
• and
• an amplitude control circuit configured to control an upper limit value and a lower limit value of the potential of the output node of said first and second inverter circuits limited by said upper/lower limit circuit.

A disc playback system comprising:

• a voltage controlled oscillator configured to generate an internal clock;
• and
• a semiconductor circuit configured to operate in response to said internal clock,
• said voltage controlled oscillator including:
• an oscillation controller configured to generate first and second control potentials corresponding to an input voltage;
• first and second current sources configured to generate control currents corresponding to said first and second control potentials, respectively;
• an oscillation section, connected to a power source potential node via said first current source and connected to a ground potential node via said second current source, said oscillation section generating said internal clock whose oscillation frequency is determined by said control current;
• a first fluctuation transmitter, disposed between said power source potential node and said first control potential node, said first fluctuation transmitter transmitting a potential fluctuation generated in said power source potential node to said first control potential node at the same phase and maintaining a potential difference between the power source potential and the first control potential to be constant;
• and
• a second fluctuation transmitter, disposed between said ground potential node and said second control potential node, said second fluctuation transmitter transmitting the potential fluctuation generated in said ground potential node to said second control potential node at the same phase and maintaining the potential difference between the ground potential and the second control potential to be constant.