A device comprising: a voltage reference supply, configured to provide a reference voltage that varies in response to temperature according to a predefined relationship; a temperature sensor providing a temperature signal indicating a temperature; a first controller configured to receive the temperature signal and to output a control signal; an LC-DCO receiving the reference voltage and providing an output signal with a frequency from an LC circuit, the LC-DCO comprising a switched capacitor bank configured to provide temperature compensation by varying an effective capacitance in the LC circuit in response to the control signal.

An oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.

In some aspects, a wireless sensor device includes a voltage controlled oscillator. The voltage controlled oscillator includes a resonator circuit, a multiplexer and control logic. The resonator circuit includes a switched capacitor bank operable to tune the resonator circuit. The multiplexer is communicatively coupled to the switched capacitor bank to select combinations of capacitor bank elements based on input values representing digital capacitance levels. The multiplexer includes a first multi-bit input configured to receive a first set of values representing a first combination of the capacitor bank elements; a second multi-bit input configured to receive a second set of values representing a second combination of the capacitor bank elements; and a multi-bit output configured to communicate the first or second set of values to the switched capacitor bank. The control logic is configured to generate the first and second sets of values for each of the digital capacitance levels.

An oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.

A frequency calibration method for calibrating an output frequency of a voltage-controlled oscillator is provided. The voltage-controlled oscillator includes a first capacitor bank, a second capacitor bank, and a third capacitor bank. The first capacitor bank and the third capacitor bank are initially disabled and the second capacitor bank is initially enabled. The method includes, when the initial output frequency is lower than a reference frequency, adjusting the capacitance of the second capacitor bank until the calibrated output frequency is greater than the reference frequency, and when the initial output frequency is greater than the reference frequency, enabling the first capacitor bank and gradually increasing the capacitance of the first capacitor bank until the calibrated output frequency is lower than the reference frequency.

A crystal oscillator includes a current source that charges a capacitor. A charge on the capacitor is periodically injected into a crystal of the crystal oscillator. A switch couples the capacitor to the crystal and a timing circuit controls the switch to cause the charge to be injected beginning at approximately a peak of a crystal output signal. The timing circuit is configurable into a self-resonant mode for calibration of a delay through the timing circuit by coupling an output of the timing circuit to an input of the timing circuit. A comparator compares a magnitude of the crystal output signal to a reference voltage and supplies compare results to a gain control circuit. The gain control circuit adjusts the current from the current source to adjust the charge being injected into the crystal from the capacitor to thereby control the magnitude of the crystal output signal.

A crystal oscillator includes a current source that charges a capacitor. A charge on the capacitor is periodically injected into a crystal of the crystal oscillator. A switch couples the capacitor to the crystal and a timing circuit controls the switch to cause the charge to be injected beginning at approximately a peak of a crystal output signal. The timing circuit is configurable into a self-resonant mode for calibration of a delay through the timing circuit by coupling an output of the timing circuit to an input of the timing circuit. A comparator compares a magnitude of the crystal output signal to a reference voltage and supplies compare results to a gain control circuit. The gain control circuit adjusts the current from the current source to adjust the charge being injected into the crystal from the capacitor to thereby control the magnitude of the crystal output signal.