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.

A digital phase-locked loop (DPLL) includes a time-to-digital converter (TDC) having a first clock input, a second clock input, and a TDC output. The DPLL includes a digital loop filter (DLF). The DLF output controls a numerically-controlled bulk acoustic wave oscillator (NCBO). The NCBO output is divided down a fractional-N divider and is fed back to the TDC. The NCBO includes a reference oscillator, a phase and/or frequency detector, a charge pump, a loop filter, a voltage-controlled bulk acoustic wave oscillator (VCBO) and a feedback fractional-N divider that has a numerical control input, which is controlled by DLF output of DPLL. The NCBO forms a stable feedback loop and have a loop bandwidth much wider than DPLL loop bandwidth. In steady state, the NCBO output frequency can be linearly numerically adjusted. An auxiliary PLL or a fractional output divider can be used to generate additional needed frequencies.

A digital phase-locked loop (DPLL) includes a time-to-digital converter (TDC) having a first clock input, a second clock input, and a TDC output. The DPLL includes a digital loop filter (DLF). The DLF output controls a numerically-controlled bulk acoustic wave oscillator (NCBO). The NCBO output is divided down a fractional-N divider and is fed back to the TDC. The NCBO includes a reference oscillator, a phase and/or frequency detector, a charge pump, a loop filter, a voltage-controlled bulk acoustic wave oscillator (VCBO) and a feedback fractional-N divider that has a numerical control input, which is controlled by DLF output of DPLL. The NCBO forms a stable feedback loop and have a loop bandwidth much wider than DPLL loop bandwidth. In steady state, the NCBO output frequency can be linearly numerically adjusted. An auxiliary PLL or a fractional output divider can be used to generate additional needed frequencies.

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 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.

Embodiments provide a data transmitter having a transmitter configured to transmit a signal, wherein at least one signal parameter of the signal depends on an environmental parameter in an environment of the data transmitter, and a shielding unit configured to shield the transmitter or part of the transmitter from the environmental parameter to reduce a receiver-side reconstructable effect of the environmental parameter on the at least one signal parameter and/or a modifier for modifying the signal parameter configured to modify the at least one signal parameter to reduce a receiver-side reconstructable effect of the environmental parameter on the at least one signal parameter, wherein the modifier for modifying the signal parameter is configured to modify the at least one signal parameter directly or a signal derived from a clock signal of a clock generator of the data transmitter on which the signal or generation of the signal depends, in order to modify the at least one signal parameter.

Embodiments provide a data transmitter having a transmitter configured to transmit a signal, wherein at least one signal parameter of the signal depends on an environmental parameter in an environment of the data transmitter, and a shielding unit configured to shield the transmitter or part of the transmitter from the environmental parameter to reduce a receiver-side reconstructable effect of the environmental parameter on the at least one signal parameter and/or a modifier for modifying the signal parameter configured to modify the at least one signal parameter to reduce a receiver-side reconstructable effect of the environmental parameter on the at least one signal parameter, wherein the modifier for modifying the signal parameter is configured to modify the at least one signal parameter directly or a signal derived from a clock signal of a clock generator of the data transmitter on which the signal or generation of the signal depends, in order to modify the at least one signal parameter.

A method for cancelling phase noise in a radar signal is described herein. In accordance with one embodiment, the method includes transmitting an RF oscillator signal, which represents a local oscillator signal including phase noise, to a radar channel and receiving a respective first RF radar signal from the radar channel. The first RF radar signal included at least one radar echo of the transmitted RF oscillator signal. Further, the method includes applying the RF oscillator signal to an artificial radar target composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal. The second RF radar signal is modulated by a modulation signal thus generating a frequency-shifted RF radar signal. Further, the method includes subtracting the frequency-shifted RF radar signal from the first RF radar signal.

A method for cancelling phase noise in a radar signal is described herein. In accordance with one embodiment, the method includes transmitting an RF oscillator signal, which represents a local oscillator signal including phase noise, to a radar channel and receiving a respective first RF radar signal from the radar channel. The first RF radar signal included at least one radar echo of the transmitted RF oscillator signal. Further, the method includes applying the RF oscillator signal to an artificial radar target composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal. The second RF radar signal is modulated by a modulation signal thus generating a frequency-shifted RF radar signal. Further, the method includes subtracting the frequency-shifted RF radar signal from the first RF radar signal.

A circuit and method include using a first source follower of a first type to receive a first voltage from a first node and output a first current to a third node; using a second source follower of a second type to receive a second voltage from a second node and output a second current to the third node; using an AC (alternate current) coupling capacitor to couple the first node to the second node; using a feedback capacitor to couple the third node to the first node; using a shunt capacitor to shunt the third node to an AC ground; using a crystal to shunt the first node to an AC ground; providing a first bias voltage to the first node via a first DC (direct current) coupling resistor; and providing a second bias voltage to the second node via a second DC coupling resistor.