Patent ID: 6803831
Filing Date: 2004-10-12
Classification: H03K

Abstract:
A ring oscillator comprising:a current control unit, including a basic current source having a series circuit formed of a first P channel transistor, the drain and the gate of which are connected, and a first N channel transistor, the drain of which is connected to the drain of the first P channel transistor and which, to supply a sub-threshold current, is operated in a weak inversion state, and a current mirror circuit having a series circuit formed of a second P channel transistor, the gate of which is connected to the drain of the first P channel transistor, a second N channel transistor, the drain and the gate of which are connected to the drain of the second P channel transistor; and a ring oscillation unit, including a current starved inverter, having a current control P channel transistor, the source of which is connected to the power source and the gate of which is connected to the drain of the first P channel transistor of the basic current source, a signal transmission P channel transistor, the source of which is connected to the drain of the current control P channel transistor, a signal transmission N channel transistor, the drain of which is connected to the drain of the signal transmission P channel transistor, and a current control N channel transistor, the drain of which is connected to the source of the signal transmission N channel transistor, the gate of which is connected to the drain of the second N channel transistor of the current mirror circuit, and the source of which is grounded, wherein a connection point of the gate of the signal transmission P channel transistor and the gate of the signal transmission N channel transistor serves as a signal input terminal, and a connection point of the drain of the signal transmission P channel transistor and the drain of the signal transmission N channel transistor serves as an output terminal for outputting an inverted signal; and an in-phase signal transmitter for receiving an input signal from the output terminal of the current starved inverter, and for outputting, to the input terminal of the current starved inverter and to an external device, a signal having the same phase as the input signal.