Variable reactance apparatus for dynamic gain switching of tunable oscillator

A variable reactance apparatus, the apparatus comprising:

• a plurality of unit variable reactance structures connected in parallel, wherein each of the plurality of unit variable reactance structures comprises a respective one of a plurality of control input nodes;
• and
• a control circuit operably coupled to the plurality of unit variable reactance structures and configured to selectively connect, based on one or more selection signals, each of the plurality of control input nodes to a respective signal from among a plurality of signals, wherein the plurality of signals comprises a first tuning signal, a second tuning signal, and an off-state control signal, wherein:
• each unit variable reactance structure within the plurality of unit variable reactance structures comprises
• a respective one of a plurality of pairs of alternating current (AC) coupling capacitors, and
• a respective one of a plurality of bias signal nodes;
• and
• the control circuit is further configured to connect an on-state bias signal to each bias signal node within a unit variable reactance structure having its respective control input node connected to the first tuning signal or the second tuning signal, and connect an off-state bias signal to each bias signal node within a unit variable reactance structure having its respective control input node connected to the off-state control signal.

A tunable oscillator, comprising:

• a resonance circuit;
• a negative impedance structure operably coupled to the resonance circuit;
• and
• a variable reactance apparatus operably coupled to the resonance circuit and configured for tuning of the oscillator, wherein the variable reactance apparatus comprises
• a plurality of unit variable reactance structures connected in parallel, wherein each of the plurality of unit variable reactance structures comprises a respective one of a plurality of control input nodes, and
• a control circuit operably coupled to the plurality of unit variable reactance structures and configured to selectively connect, based on one or more selection signals, each of the plurality of control input nodes to a respective signal from among a plurality of signals, wherein the plurality of signals comprises a first tuning signal and a second tuning signal, wherein:
• the first tuning signal comprises a modulation voltage associated with a high-pass path in a two-point injection frequency synthesizer circuit;
• and
• the second tuning signal comprises a tuning voltage associated with a low-pass path in the two-point injection frequency synthesizer circuit.

A method for changing a gain associated with an input signal of a tunable oscillator, wherein the oscillator comprises a variable reactance apparatus comprising a plurality of unit variable reactance structures connected in parallel, and each of the unit variable reactance structures within the plurality of unit variable reactance structures comprises a respective one of a plurality of pairs of AC coupling capacitors and a respective one of a plurality of bias signal nodes, the method comprising:

• connecting a first tuning signal to control input nodes of a first set of unit variable reactance structures within the plurality of unit variable reactance structures, wherein
• each of the plurality of unit variable reactance structures comprises a respective control input node, and
• the first set comprises a first number of unit variable reactance structures;
• connecting a second tuning signal to control input nodes of a second set of unit variable reactance structures within the plurality of unit variable reactance structures, wherein the second set comprises a second number of unit variable reactance structures;
• subsequently altering connections of the first tuning signal and second tuning signal to change the first and second numbers of unit variable reactance structures while holding constant a sum of the first and second numbers of unit variable reactance structures,
• connecting an on-state bias signal to each bias signal node of a unit variable reactance structure within the first set or second set of unit variable reactance structures;
• connecting an off-state control signal to control input nodes of a third set of unit variable reactance structures within the plurality of unit variable reactance structures;
• and
• connecting an off-state bias signal to each bias signal node within the third set of unit variable reactance structures.

A tunable oscillator, comprising:

• a resonance circuit;
• a negative impedance structure operably coupled to the resonance circuit;
• and
• a variable reactance apparatus operably coupled to the resonance circuit and configured for tuning of the oscillator, wherein the variable reactance apparatus comprises
• a plurality of unit variable reactance structures connected in parallel, wherein each of the plurality of unit variable reactance structures comprises a respective one of a plurality of control input nodes, and
• a control circuit operably coupled to the plurality of unit variable reactance structures and configured to selectively connect, based on one or more selection signals, each of the plurality of control input nodes to a respective signal from among a plurality of signals, wherein the plurality of signals comprises a first tuning signal, a second tuning signal, and an off-state control signal,
• wherein:
• each of the unit variable reactance structures within the plurality of unit variable reactance structures comprises
• a respective one of a plurality of pairs of AC coupling capacitors, and
• a respective one of a plurality of bias signal nodes;
• and
• the control circuit is further configured to connect an on-state bias signal to each bias signal node within a unit variable reactance structure having its respective control input node connected to the first tuning signal or the second tuning signal, and connect an off-state bias signal to each bias signal node within a unit variable reactance structure having its respective control input node connected to the off-state control signal.