Patent ID: 7230504

Claim:
An oscillator circuit comprising: an amplifier including a first switching transistor coupled between a first node and a reference node and a second switching transistor coupled between a second node and the reference node, and wherein an output of the first switching transistor is coupled to a gate terminal of the second switching transistor and an output of the second switching transistor is coupled to a gate terminal of the first switching transistor; and one or more variable capacitance circuits coupled between the first node and the second node, wherein each variable capacitance circuit comprises: a first capacitor coupled between the first node and a third node; a second capacitor coupled between the second node and a fourth node; a third, a fourth and a fifth switching transistor interconnected to selectively couple the first and second capacitors to the reference node; wherein the third, fourth and fifth switching transistors are low voltage transistors; wherein the first and the second switching transistors are high voltage transistors.