VOLTAGE-CONTROLLED OSCILLATOR USING THRESHOLD VOLTAGE CONTROL OF SOIMOSFET

摘要

PROBLEM TO BE SOLVED: To obtain a voltage ring oscillator which operates with a low voltage and generates a variable cyclic output by coupling a control input with a transistor body and actualizing such constitution that the threshold voltage of the transistor varies when the body is charged and the oscillation frequency of the oscillator is controlled. SOLUTION: A ring oscillator is composed of transistors and at least one of the transistors has a threshold voltage which can be controlled with the voltage applied to the transistor body. The control input is coupled with the body of this transistor so that the body of the transistor can be charged with the control input. When the body is charged, the threshold voltage of the transistor varies and the oscillation frequency of the oscillator is controlled. For example, the voltage ring oscillator 200 is brought under voltage control by the control input 208. In this case, the control input 208 is coupled with the bodies of N-MOSFETs of an input inverter 202, an intermediate inverter 204, and an output inverter 206.