Disclosed herein are systems and methods for linearizing frequency chirp in a frequency-modulated continuous wave (FMCW) coherent LiDAR system. Exemplary methods can include generating a continuous wave laser signal having a frequency characteristic, in which the frequency characteristic can include a frequency chirp over a frequency band in at least one period; and receiving a signal based on the generated laser signal. The methods can further include mixing the received signal with a local oscillator signal, the local oscillator signal having the frequency characteristic; determining at least one beat frequency based on the mixed signal; sampling the mixed signal at a rate equal to at least two times the beat frequency; determining a correction signal based on the sampled signal; and applying the correction signal to the laser signal.

To prevent an undesired operating mode of voltage-controlled oscillation (VCO) circuitry from dominating a desired operating mode (e.g., an in-phase operating mode or an out-of-phase operating mode), a supply reset and ramp pulse may be provided to the VCO circuitry when switching to a new mode, such that supply voltage to the VCO circuitry is reset (e.g., set to 0 V or another reference voltage), and gradually increased or ramped up back to a steady-state voltage (e.g., used to maintain a mode) within a time duration. Additionally or alternatively, a switch control bootstrap pulse may be provided to the VCO circuitry that is bootstrapped to (e.g., applied instantaneously or concurrently with) switching the VCO circuitry to the new mode. After a time duration, the VCO circuitry may switch back to a steady-state voltage (e.g., used to maintain the new mode).

To prevent an undesired operating mode of voltage-controlled oscillation (VCO) circuitry from dominating a desired operating mode (e.g., an in-phase operating mode or an out-of-phase operating mode), a supply reset and ramp pulse may be provided to the VCO circuitry when switching to a new mode, such that supply voltage to the VCO circuitry is reset (e.g., set to 0 V or another reference voltage), and gradually increased or ramped up back to a steady-state voltage (e.g., used to maintain a mode) within a time duration. Additionally or alternatively, a switch control bootstrap pulse may be provided to the VCO circuitry that is bootstrapped to (e.g., applied instantaneously or concurrently with) switching the VCO circuitry to the new mode. After a time duration, the VCO circuitry may switch back to a steady-state voltage (e.g., used to maintain the new mode).

To prevent an undesired operating mode of voltage-controlled oscillation (VCO) circuitry from dominating a desired operating mode (e.g., an in-phase operating mode or an out-of-phase operating mode), a supply reset and ramp pulse may be provided to the VCO circuitry when switching to a new mode, such that supply voltage to the VCO circuitry is reset (e.g., set to 0 V or another reference voltage), and gradually increased or ramped up back to a steady-state voltage (e.g., used to maintain a mode) within a time duration. Additionally or alternatively, a switch control bootstrap pulse may be provided to the VCO circuitry that is bootstrapped to (e.g., applied instantaneously or concurrently with) switching the VCO circuitry to the new mode. After a time duration, the VCO circuitry may switch back to a steady-state voltage (e.g., used to maintain the new mode).

Techniques are described for staggered-bias varactors. For example, a staggered-bias varactor can include a control voltage node, a number of bias voltage nodes, and a number of sub-varactors coupled in parallel. The control voltage node can be configured to receive a single, variable control voltage; and the bias voltage nodes can each be configured to receive a different, fixed bias voltage. Each sub-varactor is configured, so that its equivalent capacitance is a function of a difference between the control voltage and a respective one of the bias voltages; and the equivalent capacitance of the staggered-bias varactor is a function of the capacitances of the component sub-varactors. The number of varactors and the bias voltages can be configured, so that respective non-linear capacitive responses of the component sub-varactors effectively combine to yield a substantially linear capacitive response for the staggered-bias varactor as a whole.

Examples are disclosed that relate to oscillator circuits. One example provides a circuit comprising an amplifier, a resonator in parallel with the amplifier, and a shunt path including one or more circuit elements, the shunt path coupled to a first node downstream of an output of the amplifier and to a second node, the shunt path configured to shunt current received at the first node away from an input of the resonator and toward the second node, the second node having, at steady state, a relatively lower voltage than an input voltage of the resonator.

To prevent an undesired operating mode of voltage-controlled oscillation (VCO) circuitry from dominating a desired operating mode (e.g., an in-phase operating mode or an out-of-phase operating mode), a supply reset and ramp pulse may be provided to the VCO circuitry when switching to a new mode, such that supply voltage to the VCO circuitry is reset (e.g., set to 0 V or another reference voltage), and gradually increased or ramped up back to a steady-state voltage (e.g., used to maintain a mode) within a time duration. Additionally or alternatively, a switch control bootstrap pulse may be provided to the VCO circuitry that is bootstrapped to (e.g., applied instantaneously or concurrently with) switching the VCO circuitry to the new mode. After a time duration, the VCO circuitry may switch back to a steady-state voltage (e.g., used to maintain the new mode).

Examples are disclosed that relate to oscillator circuits. One example provides a circuit comprising an amplifier, a resonator in parallel with the amplifier, and a shunt path including one or more circuit elements, the shunt path coupled to a first node downstream of an output of the amplifier and to a second node, the shunt path configured to shunt current received at the first node away from an input of the resonator and toward the second node, the second node having, at steady state, a relatively lower voltage than an input voltage of the resonator.

A digital modulating device includes an oscillator that generates an oscillation signal, and a frequency doubling modulator that includes: a single-ended to differential converter converting the oscillation signal into two periodic signals; two inductors respectively receiving the periodic signals and respectively providing two input signals; a switching circuit; and two amplifier circuits. When the switching circuit operates in a first state, the amplifier circuits respectively amplify the input signals to respectively generate two amplified signals that are combined into a combined signal at a common node thereof. When the switching circuit operates in a second state, the amplifier circuits do not perform amplification.

A digital modulating device includes an oscillator that generates an oscillation signal, and a frequency doubling modulator that includes: a single-ended to differential converter converting the oscillation signal into two periodic signals; two inductors respectively receiving the periodic signals and respectively providing two input signals; a switching circuit; and two amplifier circuits. When the switching circuit operates in a first state, the amplifier circuits respectively amplify the input signals to respectively generate two amplified signals that are combined into a combined signal at a common node thereof. When the switching circuit operates in a second state, the amplifier circuits do not perform amplification.