Abstract: An integrated clock generator includes a tunable LC oscillator, a tunable frequency synthesizer, and a processor. The tunable LC oscillator has an input for receiving an oscillator control signal, and an output for providing an oscillator clock signal. The tunable frequency synthesizer has a clock input coupled to the output of the tunable LC oscillator, a control input for receiving a synthesizer control signal, and an output for providing a clock output signal. The processor has an input for receiving a data input signal, a first output for providing the oscillator control signal, and a second output for providing the synthesizer control signal. The processor provides the oscillator control signal and the synthesizer control signal such that the tunable frequency synthesizer generates the output clock signal at a frequency indicated by the data input signal, and provides the synthesizer control signal further in response to a dynamic condition.

Abstract: A technique for sensing an environmental parameter is disclosed. The technique generates an oscillating signal using a variable resistance sensitive to a variable parameter. A frequency of the oscillating signal is directly dependent on the variable resistance. A time-to-digital converter generates a digital code indicative of the variable resistance. The digital code is generated based on the frequency of the oscillating signal and a second frequency of a reference clock signal. The second frequency is insensitive to the variable parameter. The variable resistance may be a metal resistor and the reference resistance may be generated using a capacitor that is switched at a particular frequency. The measured resistance may be used to control a voltage-controlled oscillator. The oscillating signal frequency may be converted to a digital signal and post-processed for use as an indicator of absolute temperature or other environmental parameter.

Abstract: A technique for sensing an environmental parameter is disclosed. The technique generates an oscillating signal using a variable resistance sensitive to a variable parameter. A frequency of the oscillating signal is directly dependent on the variable resistance. A time-to-digital converter generates a digital code indicative of the variable resistance. The digital code is generated based on the frequency of the oscillating signal and a second frequency of a reference clock signal. The second frequency is insensitive to the variable parameter. The variable resistance may be a metal resistor and the reference resistance may be generated using a capacitor that is switched at a particular frequency. The measured resistance may be used to control a voltage-controlled oscillator. The oscillating signal frequency may be converted to a digital signal and post-processed for use as an indicator of absolute temperature or other environmental parameter.

Abstract: A technique that reduces or eliminates trading-off power amplifier efficiency and costly external filtering in amplitude and phase modulated sinusoidal signal generation uses multi-phase outphasing and a multi-phase switching mode power amplifier to generate the amplitude and phase modulated sinusoidal signals. The technique combines multiple clock phases with sinusoidally weighted circuits of the switching mode power amplifier to improve amplitude and phase modulated sinusoidal signal generation.

Abstract: A low-complexity differential inductor and common-mode impedance network for reducing effects of flicker noise in an oscillator output signal have been disclosed. An oscillator includes a planar conductive loop comprising a first terminal, a second terminal, and a center tap. The planar conductive loop is formed from a first conductive layer above an integrated circuit substrate. The center tap is coupled to a first power supply node. The oscillator includes a planar conductive structure extending from a first point proximate to the center tap. The planar conductive structure extends along a line of symmetry of the planar conductive loop to a second point proximate to the first terminal and the second terminal. The planar conductive structure may be formed from the first conductive layer and may be directly coupled to the center tap.

Abstract: A technique for on-chip time measurement includes dynamically scaling a range of a time-based digital-to-analog converter to enhance resolution of the time measurement. An apparatus includes a first time-based digital-to-analog converter configured to generate a first clock signal based on a first reference clock signal and a first digital code. The apparatus includes a second time-based digital-to-analog converter configured to generate a second clock signal based on a second reference clock signal and a second digital code. The first reference clock signal has a first frequency and the second reference clock signal has a second frequency that is harmonically related to the first frequency. The apparatus includes a time signal converter configured to generate an output signal having a level indicative of a time-of-arrival of a first edge of the first clock signal relative to a time-of-arrival of a second edge of the second clock signal.

Abstract: A low-complexity differential inductor and common-mode impedance network for reducing effects of flicker noise in an oscillator output signal have been disclosed. An oscillator includes a planar conductive loop comprising a first terminal, a second terminal, and a center tap. The planar conductive loop is formed from a first conductive layer above an integrated circuit substrate. The center tap is coupled to a first power supply node. The oscillator includes a planar conductive structure extending from a first point proximate to the center tap. The planar conductive structure extends along a line of symmetry of the planar conductive loop to a second point proximate to the first terminal and the second terminal. The planar conductive structure may be formed from the first conductive layer and may be directly coupled to the center tap.

Abstract: A low-noise voltage reference generator that utilizes internal gain and feedback to generate an output signal having reduced sensitivity to power supply variations and loading conditions is described. A method includes generating a current based on a voltage drop across a resistor. The voltage drop is based on a second voltage drop across a gate terminal of a transistor and a source terminal of the transistor. The method includes the current using a reference voltage to generate a mirrored current through a node coupled to the drain terminal of the transistor. The method includes generating a level-shifted voltage using a voltage on the node. The method includes buffering the level-shifted voltage using a power supply voltage to generate the reference voltage.

Abstract: Techniques for reducing error in time-of-flight measurement due to transceiver latency are disclosed. A method includes determining a first indicator of a first latency of a first transceiver of a first system using a first loopback configuration of the first transceiver. The method includes receiving a second indicator of a second latency of a second transceiver determined by a second system using a second loopback configuration of the second transceiver. The method includes determining a third indicator of a roundtrip latency of a communication from the first transceiver to the second transceiver and back to the first transceiver. The method includes determining a time-of-flight between the first system and the second system based on the first indicator, the second indicator, and the third indicator.

Abstract: A technique for reducing noise in an output clock signal of a feedback control system (e.g., a PLL or FLL) samples rising edge errors and falling edge errors between a reference clock signal and a feedback clock signal. The technique applies edge alignment correction to reduce or eliminate edge alignment errors between the reference clock signal and the feedback clock signal. A PLL generates an output clock signal based on a control signal generated using an error signal generated based on a rising edge difference between a rising edge of an input clock signal and a corresponding edge of an edge alignment corrected feedback clock signal and based on a falling edge difference between a falling edge of the input clock signal and a corresponding edge of the edge alignment corrected feedback clock signal. The edge alignment corrected feedback clock signal is partially based on the output clock signal.

Abstract: An oscillator amplifier biasing technique configures an oscillator amplifier to operate at a bias point causing loading on a tank circuit to have reduced or negligible dependence on amplifier bias conditions or device characteristics. The bias signal level may vary with variation in temperature. The oscillator amplifier biasing technique includes determining a bias signal level that has a minimum sensitivity of the frequency of oscillation as a function of temperature. The technique may store associated data in non-volatile memory to describe the bias signal level dependence on temperature. A digital-to-analog converter may drive the bias signal of the oscillator to the minimum sensitivity point as a function of temperature. The technique may substantially reduce effects of up-conversion of flicker noise in the oscillator output signal as well as improve frequency accuracy in the presence of effects such as mechanical strain and/or aging.

Abstract: An oscillator system addresses power supply noise and temperature dependence. The system includes a multi-stage regulator circuit that receives a supply voltage and generates a lower voltage oscillator supply voltage that is less noisy than the supply voltage. A charge pump circuit receives the oscillator supply voltage and the oscillator output signal and supplies the regulator circuit with a boosted voltage. A reference generator circuit supplies a reference signal that is used to determine the oscillator supply voltage. The reference signal varies with temperature and is used to offset the temperature coefficient of the oscillator.

Abstract: Techniques for reducing error in time-of-flight measurement due to transceiver latency are disclosed. A method includes determining a first indicator of a first latency of a first transceiver of a first system using a first loopback configuration of the first transceiver. The method includes receiving a second indicator of a second latency of a second transceiver determined by a second system using a second loopback configuration of the second transceiver. The method includes determining a third indicator of a roundtrip latency of a communication from the first transceiver to the second transceiver and back to the first transceiver. The method includes determining a time-of-flight between the first system and the second system based on the first indicator, the second indicator, and the third indicator.

Abstract: A technique for calibrating a digital-to-time converter includes an apparatus including a digital-to-time converter configured to generate an output signal based on a digital code, an input signal, and a gain calibration signal. The output signal has edges linearly delayed from corresponding edges of the input signal based on the digital code. The digital code vacillates between an evaluation code and a calibration code. The apparatus includes a reference signal generator configured to provide a delayed version of the input signal. The delay of the reference signal generator is matched to a delay of the digital-to-time converter. The apparatus includes a calibration circuit configured to generate the gain calibration signal based on the output signal and the delayed version of the input signal. The calibration code may alternate between a first calibration delay code and a second calibration delay code.

Abstract: A technique for calibrating a digital-to-time converter includes an apparatus including a digital-to-time converter configured to generate an output signal based on a digital code, an input signal, and a gain calibration signal. The output signal has edges linearly delayed from corresponding edges of the input signal based on the digital code. The digital code vacillates between an evaluation code and a calibration code. The apparatus includes a reference signal generator configured to provide a delayed version of the input signal. The delay of the reference signal generator is matched to a delay of the digital-to-time converter. The apparatus includes a calibration circuit configured to generate the gain calibration signal based on the output signal and the delayed version of the input signal. The calibration code may alternate between a first calibration delay code and a second calibration delay code.

Abstract: A technique for reducing series resistance of an inductor system, which may increase the quality factor of the inductor system, has been disclosed. An apparatus includes a conductive loop formed from a first conductive layer. The conductive loop comprises a first terminal and a second terminal. The first terminal includes at least one first conductive finger in the first conductive layer. The second terminal includes at least one second conductive finger in the first conductive layer. The at least one second conductive finger is interdigitated with the at least one first conductive finger without directly contacting the at least one first conductive finger. The apparatus may include a serpentine gap in the first conductive layer. The apparatus may include at least one first conductive via coupled to a second conductive layer and coupled the at least one first conductive fingers, respectively.

Abstract: An apparatus includes a microelectromechanical system (MEMS) device. The MEMS device includes a resonator suspended from a substrate, an anchor disposed at a center of the resonator, a plurality of suspended beams radiating between the anchor and the resonator, a plurality of first electrodes disposed about the anchor, and a plurality of second electrodes disposed about the anchor. The plurality of first electrodes and the resonator form a first electrostatic transducer. The plurality of second electrodes and the resonator form a second electrostatic transducer. The first electrostatic transducer and the second electrostatic transducer are configured to sustain rotational vibrations of the resonator at a predetermined frequency about an axis through the center of the resonator and orthogonal to a plane of the substrate in response to a signal on the first electrode.

Abstract: Reference signal generators using thermistors are disclosed. An apparatus includes a first device having a first temperature coefficient and a thermistor having a second temperature coefficient having a sign opposite to that of the first temperature coefficient. A circuit maintains equivalence of a first signal and a second signal and offsets a first temperature variation of the first device using a second temperature variation of the thermistor to generate the second signal having a low temperature coefficient. The first device may be a bipolar transistor configured to generate a base-emitter voltage and coupled in series with the thermistor. The first signal may be a first voltage on a first node. The second signal may be a second voltage on a second node. The circuit may be configured to maintain effective equivalence of the first voltage and the second voltage. The apparatus may include a resistor coupled to the second node.

Abstract: Various techniques for automatic amplitude control of an oscillator are described. An apparatus includes an oscillator circuit configured to generate an oscillating signal. The apparatus includes a feedback circuit configured to control a bias signal of the oscillator circuit to maintain a target peak amplitude of the oscillating signal based on a current-mode indicator of a peak amplitude of the oscillating signal and a reference current. The feedback loop includes a rectifier circuit configured to generate the current-mode indicator and a summing node configured to provide a bias control signal based on a difference between the current-mode indicator and the reference current. The feedback circuit may include a capacitor coupled to the summing node and configured to accumulate charge according to the difference. A magnitude of the current-mode indicator may be at least two orders of magnitude less than a magnitude of the current through an output node of the oscillator circuit.

Abstract: An integrated clock generator includes a tunable LC oscillator, a tunable frequency synthesizer, and a processor. The tunable LC oscillator has an input for receiving an oscillator control signal, and an output for providing an oscillator clock signal. The tunable frequency synthesizer has a clock input coupled to the output of the tunable LC oscillator, a control input for receiving a synthesizer control signal, and an output for providing a clock output signal. The processor has an input for receiving a data input signal, a first output for providing the oscillator control signal, and a second output for providing the synthesizer control signal. The processor provides the oscillator control signal and the synthesizer control signal such that the tunable frequency synthesizer generates the output clock signal at a frequency indicated by the data input signal, and provides the synthesizer control signal further in response to a dynamic condition.