Patent ID: 8134414

Claim:
An apparatus to generate a harmonic reference signal, the apparatus comprising: a reference resonator configured to generate a first reference signal having a resonant frequency, the reference resonator comprising a first component having a first temperature dependence; and a plurality of switchable circuits couplable to the reference resonator, at least one switchable circuit of the plurality of switchable circuits having a second temperature dependence opposing the first temperature dependence to maintain the resonant frequency within a predetermined variance over a temperature variation; wherein each switchable circuit of the plurality of switchable circuits comprises: a first reactance coupled in series with a first switch; a resistor; a second reactance coupled to the resistor; and a second switch coupled in series to the second reactance or to the resistor; wherein the first switch is responsive to a control signal of a plurality of control signals to electronically couple or decouple the first reactance to or from a voltage, a ground potential, or the reference resonator; and wherein the second switch is responsive to an inverted control signal of a plurality of control signals to electronically couple or decouple the second reactance or the resistor to or from a voltage, a ground potential, or the reference resonator.