Structure for an inductor-capacitor voltage-controlled oscillator

摘要

Embodiments of the present invention provide a design structure and method for compensating for a change in frequency of oscillation (FOO) of an LC-tank VCO that includes a first node; second node; inductor; first capacitive network (FCN) that allows the design structure to obtain a target FOO; compensating capacitive (CCN) network that compensates for a change in the design structure's FOO; second capacitive network (SCN) that allows the design structure to obtain a desired FOO; a filter that supplies a voltage to the SCN and is coupled to the SCN; a transconductor that compensates for a change in the design structure's FOO; and a sub-circuit coupled to the SCN that generates and supplies voltage to the CCN sufficient to allow the CCN to compensate for a reduction in the design structure's FOO. The first and second nodes are coupled to the inductor, FCN, CCN, SCN, and sub-circuit.

主权项

1. A circuit, comprising:
a first node; a second node; an inductor coupled to the first node and the second node; a first capacitive network coupled to the first node and second node, wherein the first capacitive network is designed to allow the circuit to obtain an approximate target frequency of oscillation; a compensating capacitive network coupled to the first node and the second node, wherein the compensating capacitive network is designed to compensate for a change in frequency of oscillation of the circuit caused by a supply voltage dependence of the circuit; a second capacitive network coupled to the first node and the second node, wherein the second capacitive network allows the circuit to obtain a desired frequency of oscillation; a filter coupled to the second capacitive network, wherein the filter supplies a voltage to the second capacitive network; a transconductor coupled to the first node and the second node, wherein the transconductor is designed to compensate for a change in the frequency of oscillation in the circuit; and a sub-circuit coupled to the compensating capacitive network, wherein the sub-circuit generates and supplies voltage to the compensating capacitive network sufficient to allow the compensating capacitive network to compensate for a reduction in frequency of oscillation of the circuit, and wherein the sub-circuit includes at least one field-effect transistor gate-coupled to a node via another node, wherein the sub-circuit comprises:
a first resistor coupled to a supply voltage;a second resistor coupled to the first resistor via a first node;a first field-effect transistor gate-coupled to the first node via a second node, wherein the first field-effect transistor is source-coupled to the supply voltage, and wherein the first field-effect transistor is drain-coupled to a third resistor via a third node;a second field-effect transistor gate-coupled to the third node via a fourth node, wherein the first field-effect transistor is source-coupled to the supply voltage, and wherein the second field-effect transistor is drain-coupled to a fourth resistor via a fifth node;a third field-effect transistor gate-coupled to the fifth node via a sixth node, wherein the third field-effect transistor is source-coupled to the supply voltage, and wherein the third field-effect transistor is drain-coupled to a fifth resistor via a seventh node;wherein the second resistor, third resistor, fourth resistor, and fifth resistor are ground coupled; andwherein the sub-circuit to the compensating capacitive network via an eighth node.