A resonator oscillator that may be included in a gas sensing system may include an oscillator that may be electrically connected to an external resonator through a conductive line. The oscillator may generate an oscillating signal having a frequency corresponding to a resonance frequency of the external resonator in an oscillating path. A spurious resonance removal circuit on the oscillating path may remove spurious resonance caused by the conductive line from the oscillating path. A gas sensing system may include the oscillator, a resonator that includes a sensor configured to sense a gas, and a frequency counting logic that receives the oscillating signal and a reference clock signal, performs a counting operation on the oscillating signal according to a logic state of the reference clock signal to generate a counted value, and generate a gas sensing output indicating a sensed gas based on the counted value.

A frequency synthesizer comprising a first phase locked loop (PLL) circuit coupled to receive a reference frequency signal from a reference oscillator, the first PLL circuit comprising a first voltage controlled oscillator (VCO) having a bulk acoustic wave (BAW) resonator and a first fractional feedback divider circuit, the first PLL circuit outputting a first tuned frequency signal and a first plurality of integer divider circuits coupled to receive the first tuned frequency signal from the first PLL circuit and each of the first plurality of integer-only post-PLL divider circuits to provide one of a plurality of output frequency signals of the frequency synthesizer.

A clock oscillator includes with a pullable BAW oscillator to generate an output signal with a target frequency. The BAW oscillator is based on a BAW resonator and voltage-controlled variable load capacitance, responsive to a capacitance control signal to provide a selectable load capacitance. An oscillator driver (such as a differential negative gm transconductance amplifier), is coupled to the BAW oscillator to provide an oscillation drive signal. The BAW oscillator is responsive to the oscillation drive signal to generate the output signal with a frequency based on the selectable load capacitance. The oscillator driver can include a bandpass filter network with a resonance frequency substantially at the target frequency.

In one example, an apparatus comprises an oscillator having a control input and a clock output. The apparatus also comprises a frequency control circuit having an input and a control output, the control output coupled to the control input, and a reference clock generator having a reference clock output. The apparatus also comprises a multiplexer having a first multiplexer input, a second multiplexer input, a selection input, and a multiplexer output, the first multiplexer input coupled to the clock output, the second multiplexer input coupled to the reference clock output, and the multiplexer output coupled to the input of the frequency control circuit.

Aspects of the disclosure provide a method of using a bulk acoustic wave (BAW) based clock. For example, a first burst pulse of ultrasonic waves may be received by a transmit transducer of a BAW delay device. A feedthrough pulse from the first burst pulse may be received at a receive transducer of the BAW delay device. After receiving the feedthrough pulse, a first echo pulse from the first burst pulse may be received at the receive transducer. The first pulse may be a reflection of a portion of the first burst pulse from a substrate. A difference in time between the receipt of the feedthrough pulse and the receipt of the first echo pulse may be used to control timing of a second burst pulse of ultrasonic waves.

An oscillator includes a resonator element, an oscillation circuit configured to oscillate the resonator element to generate a clock signal, a temperature sensor, a digital control circuit configured to operate based on the clock signal and output a control signal based on a temperature detected by the temperature sensor, a temperature control circuit configured to output a control voltage based on the control signal, a temperature control element configured to control a temperature of the resonator element based on the control voltage, and a clock signal abnormality detection circuit configured to detect an abnormality in the clock signal. The clock signal abnormality detection circuit stops an output of the control voltage to the temperature control element performed by the temperature control circuit when the abnormality in the clock signal is detected.

An oscillator and method for generating a signal are provided. The oscillator comprises an electro-mechanical resonator and a reconfigurable oscillator driver. The reconfigurable oscillator driver starts the oscillator in single-ended mode to avoid latching and transitions the oscillator to differential mode in such a manner as to sustain oscillations therein. The reconfigurable oscillator driver may comprise two back-to-back banks of inverters and an adjustable feedback resistor. In single-ended mode, one bank is disabled and the other bank is enabled. To transition to differential mode and improve the quality of the signal, the number of enabled inverters is equalized in both banks.

An acoustic-wave device with active calibration mechanism is provided. The acoustic-wave device with active calibration mechanism includes at least one adjustable acoustic-wave duplexer, a frequency discriminator and a control circuit. The adjustable acoustic-wave duplexer has a first terminal point, a second terminal point and a third terminal point. The adjustable acoustic-wave duplexer includes a TX filter, an RX filter, a first loop switch and a second loop switch. The first loop switch is used for conducting a first loop. The second loop switch is used for conducting a second loop. The control circuit adjusts the operating frequency of the TX filter according to a first loop calibration signal. The control circuit adjusts the operating frequency of the operating frequency of the RX filter according to the second loop calibration signal.

An oscillation module includes a loop interconnection, a high-frequency output interconnection, a differential amplifier, and an output terminal, the differential amplifier is connected to the output terminal with the high-frequency output interconnection, the high-frequency output interconnection crosses the loop interconnection in a grade-separated manner, and the loop interconnection is different in thickness between a crossing part and a non-crossing part with the high-frequency interconnection.

Methods and systems are provided for generating balanced oscillations in oscillators. An oscillator comprises a resonator input configured to receive, from an electro-mechanical resonator, a resonator signal; and an oscillator core comprising a first and a second complementary inverters forming a first loop and a second loop with the resonator input, respectively. The inverters are programmable to contribute to the resonator signal a first gain or a second gain to generate balanced oscillations in the oscillator, with the first gain being less than an upper threshold gain required to generate parasitic-mode oscillations when starting balanced oscillations, and the second gain being equal to or greater than a lower threshold, gain required to generate resonator-mode oscillations. Each inverter is configured to regulate gain contributed by the inventor based on regulating amount of power received to control the gain.