Voltage controlled oscillation circuit
View Patent ↗In a voltage controlled oscillation circuit including a cascade connection of a voltage-to-current conversion circuit ( 310 ) for generating an input voltage converted current which is a current corresponding to an input voltage and a current controlled oscillation circuit ( 120 ) of which an oscillation frequency varies according to the input voltage converted current, the voltage-to-current conversion circuit ( 310 ) includes a first current source for outputting a current in proportion to the input voltage and a plurality of second current sources for outputting a current in proportion to a voltage obtained by shifting the input voltage. Then, a current obtained by adding a current output from the first current source and currents output from the plurality of current sources is output as the input voltage converted current to the current controlled oscillation circuit ( 120 ).
1. A voltage controlled oscillation circuit comprising:
a voltage-to-current conversion circuit, which includes a first current source and a plurality of second current sources, each being configured to output a current according to an input voltage, the voltage-to-current conversion circuit generates a current obtained by adding a current output by the first current source and currents output by the plurality of second current sources; and
a current controlled oscillation circuit of which an oscillation frequency varies according to a value of an output current of the voltage-to-current conversion circuit, wherein:
the first current source includes a first MOS transistor and is configured so that the input voltage is applied to a gate of the first MOS transistor, an end of a current path of the first MOS transistor is connected to a reference voltage via a first resistor and a second resistor, and thereby a current is caused to pass through the current path, and
each of the plurality of second current sources includes a second MOS transistor and is configured so that a voltage at a connection node of the first resistor and the second resistor is provided to a gate of the second MOS transistor, an end of a current path of the second MOS transistor is connected to the reference voltage via at least one resistor, and thereby a current is caused to pass through the current path.
2. The voltage controlled oscillation circuit of claim 1 , wherein:
each of the first and second MOS transistors are N-channel MOS transistors, and the reference voltage is ground.