Voltage controlled oscillator (VCO) circuits

A method to control a voltage-controlled oscillator (VCO) comprising:

• generating equivalent voltage corresponding to a varistor capacitance of the VCO from a first current value, by a voltage generation circuit of a control circuit;
• and
• mapping an input control voltage to a capacitance of a varistor capacitance circuit by an error amplifier, for the varistor capacitance circuit through a voltage-controlled transistor in the varistor capacitance circuit,
• wherein the equivalent voltage is forced to be equal in value to the input control voltage by the control circuit, and wherein the equivalent voltage is utilized to map the input control voltage to a value of the capacitance for the varistor capacitance circuit.

A voltage-controlled oscillator circuit, comprising:

• an inductor-capacitor (LC) tank circuit comprising a center tapped inductor connected in parallel with a varactorless capacitor bank, wherein the LC tank circuit resonates to produce an oscillating voltage;
• and
• a control circuit connected to a varistor capacitance circuit, wherein the varistor capacitance circuit comprises a voltage-controlled transistor based variable resistor in series with at least one capacitor, the varistor capacitance circuit being connected in parallel with the LC tank circuit and to a negative trans-conductance circuit,
• wherein the control circuit comprises an error amplifier and a conversion circuit configured to generate an output control voltage based on an input control voltage, the output control voltage controlling a value of a capacitance for the varistor capacitance circuit through the voltage-controlled transistor based variable resistor, and
• wherein the conversion circuit is further configured to generate:
• a varistor capacitance as a replica of the capacitance for the varistor capacitance circuit;
• and
• the output control voltage as an equivalent voltage to map a phase locked loop control voltage to the capacitance for the varistor capacitance circuit.