Patent ID: 7015768

Claim:
A method for providing common-mode noise rejection in a voltage controlled oscillator (VCO), the method comprising: applying a first input control tuning signal to a first node, wherein the first node is shared between a first pair of varactors, each of the first pair of varactors having a positive terminal and a negative terminal, wherein at least one of the terminals represents an external node, and each of the first pair of varactors being connected in series with their respective positive terminals at the first node; applying a second input control tuning signal to a second node, wherein the second node is shared between a second pair of varactors, each of the second pair of varactors having a positive terminal and a negative terminal, wherein at least one of the terminals represents an external node, each of the second pair of varactors being connected in series with their respective negative terminals at the second node, wherein the first pair of varactors is connected in parallel with the second pair of varactors, and wherein external nodes of the first and second pairs of varactors comprise the negative terminal of each of the first pair of varactors and the positive terminal of each of the second pair of varactors; and applying a common mode signal to the external nodes of the first and second pairs of varactors using at least one passive element.