Voltage controlled oscillation circuit having easily controllable oscillation characteristic and capable of generating high frequency and low frequency internal clocks

A voltage controlled oscillation circuit comprising:

• a self-excited oscillation circuit oscillating with a frequency in accordance with a level of an operating current control signal, wherein said self-excited oscillation circuit includes
• a plurality of stages of inversion circuits connected in series to each other, and each having a field effect transistor as a switching element to operate with a current in accordance with said operating current control signal;
• and
• an operating current control circuit generating said operating current control signal in accordance with a control voltage applied from an outside of said voltage controlled oscillation circuit, wherein said operating current control circuit includes
• a current mirror circuit generating a constant current flowing from a first power supply node to a second power supply node, and outputting said operating current control signal in accordance with a value of said constant current;
• and
• a current mirror control circuit controlling the value of said constant current generated by said current mirror circuit in accordance with said control voltage, and changing a range, in which the value of said constant current is changed in response to a change of said control voltage, in accordance with an instruction signal applied from the outside of said voltage controlled oscillation circuit, wherein
• said current mirror circuit includes:
• a first field effect transistor having a source coupling to said first power supply node, and having a gate and a drain coupling to each other;
• and
• a second field effect transistor having a source coupling to said first power supply node, and having a gate coupling to the gate of said first field effect transistor, and
• said current mirror control circuit includes:
• a control voltage input circuit controlling a current value of a current directed from the drain of said first field effect transistor to said second power supply node in accordance with said control voltage, and having a current driving capability variable in accordance with said instruction signal;
• a first resistance circuit provided between said control voltage input circuit and said second power supply node;
• and
• a second resistance circuit provided between the gate of said first field effect transistor and said second power supply node.

A voltage controlled oscillation circuit comprising:

• a self-excited oscillation circuit oscillating with a frequency in accordance with a level of an operating current control signal, wherein said self-excited oscillation circuit includes
• a plurality of stages of inversion circuits connected in series to each other, and each having a field effect transistor as a switching element to operate with a current in accordance with said operating current control signal;
• and
• an operating current control circuit generating said operating current control signal in accordance with a control voltage applied from an outside of said voltage controlled oscillation circuit, wherein said operating current control circuit includes:
• a current mirror circuit generating a constant current flowing from a first power supply node to a second power supply node, and outputting said operating current control signal in accordance with a value of said constant current;
• and
• a current mirror control circuit controlling the value of said constant current generated by said current mirror circuit in accordance with said control voltage, and changing a range, in which the value of said constant current is changed in response to a change of said control voltage, in accordance with an instruction signal applied from the outside of said voltage controlled oscillation circuit, wherein
• said current mirror circuit includes:
• a first field effect transistor having a source coupling to said first power supply node, and having a gate and a drain coupling to each other;
• and
• a second field effect transistor having a source coupling to said first power supply node, and having a gate coupling to the gate of said first field effect transistor, and
• said current mirror control circuit includes:
• a control voltage input circuit controlling a current value of a current directed from the drain of said first field effect transistor to said second power supply node in accordance with said control voltage, and having a current driving capability variable in accordance with said instruction signal;
• a first resistance circuit provided between said control voltage input circuit and said second power supply node;
• and
• a second resistance circuit provided between the gate of said first field effect transistor and said second power supply node, and having a resistance value variable in accordance with said instruction signal.