Patent ID: 6292065
Filing Date: 2001-09-18
Classification: H03B,H03L

Abstract:
An inductive-capacitive (LC) voltage controlled oscillator (VCO) comprising:(a) an LC oscillator module having first and second tank nodes; and(b) a control module having positive and negative input voltage terminals, said control module in turn comprising:(b-1) a first voltage dependent capacitive element (VDCE) having positive and negative VDCE terminals, said positive terminal of said first VDCE being coupled to said negative input voltage terminal, one of said positive and negative terminals of said first VDCE being capacitively coupled to said second tank node, said first VDCE being configured to be biased for operation as a voltage-dependent variable capacitance;(b-2) a second VDCE having positive and negative VDCE terminals, said positive terminal of said second VDCE being coupled to said negative input voltage terminal, one of said positive and negative terminals of said second VDCE being capacitively coupled to said first tank node, said second VDCE being configured to be biased for operation as a voltage-dependent variable capacitance;(b-3) a third VDCE having positive and negative VDCE terminals, said negative terminal of said third VDCE being coupled to said positive input voltage terminal, one of said positive and negative terminals of said third VDCE being capacitively coupled to said second tank node, said third VDCE being configured to be biased for operation as a voltage-dependent variable capacitance; and(b-4) a fourth VDCE having positive and negative VDCE terminals, said negative terminal of said fourth VDCE being coupled to said positive input voltage terminal, one of said positive and negative terminals of said fourth VDCE being capacitively coupled to said first tank node, said fourth VDCE being configured to be biased for operation as a voltage-dependent variable capacitance;whereby:a differential voltage applied across said positive and negative input voltage terminals is operable to change capacitive properties of said VDCEs, so as to vary an output frequency of said LC oscillator module, while effects on said output frequency of a common mode voltage applied to said positive and negative input voltage terminals tend to cancel.