Abstract: Systems and methods for controlling phase or delay in multi-channel radio frequency applications. The system includes a local oscillator, a frequency generator, a clock buffer, a plurality of mixers and a plurality of filters. The frequency generator generates an intermediate frequency output signal which can be received by the clock buffer. The clock buffer creates multiple phase-adjusted reference frequency signals that are each different in phase. A local oscillator generates a plurality of local oscillator signals having the same frequency and phase. A plurality of mixers produce a plurality of RF signals based at least in part on the plurality of local oscillator signals and the plurality of phase-shifted reference frequency signals.

Abstract: According to various aspects, systems and methods for providing a soft-decoding physical unclonable function are provided. According to one embodiment, PUF circuitry includes circuit elements with impedance values that are used to generate a PUF value. For example, one or more resistors may be connected to a voltage source. The resistors may generate a resulting voltage signal that is measured and indicates a ratio of the impedance values of the resistors. Due to manufacturing variations, each impedance value may be unique, such that the impedance values may be used to provide a unique number sequence. Each ratio value may be converted into a single bit or multi-bit digital value through digitization, for example with a comparator and/or an analog to digital converter, and the series of digital values may represent or be used to generate a unique number sequence.

Abstract: A low capacitance n-channel analog switch circuit, a p-channel analog switch circuit, and a full CMOS transmission gate (T-gate) circuit are described. Resistive decoupling can be used to isolate the switch or T-gate from AC grounds. A semiconductor region that is separated from a body region of a pass field-effect transistor (FET), such as by an insulator, can be coupled to or driven to a voltage similar to the input voltage or other desired bias voltage (e.g., an operational amplifier output) to help reduce parasitic capacitance of the switch or T-gate. The switch or T-gate can help provide improved frequency bandwidth or frequency response. The switch can be useful in a programmable gain amplifier (PGA) or programmable gain instrumentation amplifier (PGIA) or other circuit in which excessive switch capacitance could degrade circuit performance.

Abstract: Apparatus and methods are disclosed related to managing characteristics of a mobile device based upon capacitive detection of materials proximate the mobile device, a capacitive gesture system that can allow the same gestures be used in arbitrary locations within range of a mobile device. One such method includes receiving a first capacitive sensor measurement with a first capacitive sensor of the mobile device. The method further includes determining a value indicative of a material adjacent to the mobile device based on a correspondence between the first capacitive sensor measurement and stored values corresponding to different materials. The method further includes sending instructions to adjust a characteristic of the mobile device based on the determined value indicative of the material adjacent to the mobile device. In certain examples, gesture sensing can be performed using capacitive measurements from the capacitive sensors.

Abstract: Techniques for an integrated slew-rate control circuit are provided. In certain examples, an adjustable, integrated slew-rate control circuit for a bypass transistor can provide three decades of adjustability. In an example, a slew-rate control circuit can include a load bypass transistor, a slew-rate control capacitor, electrically coupled between a conduction node of the load bypass transistor and a control node of the load bypass transistor, and a current mirror circuit. The current mirror circuit can include a sense transistor electrically coupled in series with the slew-rate control capacitor and the control node, and a mirror transistor electrically coupled between a power supply and the control node, to selectively provide, to or from the control node, a shunt current that bypasses the slew-rate control capacitor to limit a slew rate of a voltage at the conduction node.

Abstract: One embodiment is an apparatus including a detector circuit electrically coupled between a signal source and a second circuit, the signal source generating a first signal, the detector circuit detecting a level of the first signal and generating a first control signal when the detected level of the first signal exceeds a first threshold value, and a clamping switch electrically coupled to receive the first control signal from the detector circuit, the clamping switch including a multi-terminal active device. The first control signal controls a state of the clamping switch such that the clamping switch clamps a level of a signal applied to the second circuit when the level of the first signal exceeds the first threshold value.

Abstract: This disclosure is in the field of electronics and more specifically in the field of timing control electronics. In an example, a timing control system can include or use an array of circuit cells, and each cell can provide a signal delay using a fixed delay or interpolation. The interpolation can include, in one or more cells, using three timing signals with substantially different delays to create a delayed output signal. Linearity of the delayed output signal is thereby improved. In an example, an impedance transformation circuit can be applied to improve a bandwidth in one or more of the cells to thereby improve the bandwidth of the timing control system.

Abstract: Sound waves cause pressure changes in the air, and the pressure changes cause changes in the dielectric constant of air. Capacitive sensor measurements indicative of the changes in the dielectric constant of air can be processed to extract features associated with sound waves in the air. The features can include sound pressure levels represented and recordable as audio samples. Furthermore, the features can help identify types of sounds, determine direction of travel of the sound waves, and/or determine the source location of the audio. Instead of relying on movement of a mechanical member to transduce sound waves through a port into an electrical signal, an improved microphone uses capacitive sensing to directly sample and sense static pressure as well as dynamic pressure or pressure changes in the air to derive audio samples. The resulting microphone avoids disadvantages of the conventional microphone having the moving mechanical member and port.

Abstract: Multiple-axis resonant accelerometers are based on detection of resonance frequency changes of one or more electrostatically-driven resonator masses due to electrostatic gap changes under acceleration. Specifically, one or more resonator masses are configured to resonate simultaneously in different directions associated with different axes of sensitivity (e.g., X, Y, and/or Z axes). The motion of each resonator mass is monitored through one or more electrostatically-coupled sense electrodes. An acceleration along a particular axis of sensitivity causes a small change in the electrostatic gap(s) between the corresponding resonator mass(es) and the sense electrode(s) associated with that axis of sensitivity, and this electrostatic gap change manifests as a small change in the resonance frequency of the resonator from which an accelerometer output signal can be produced.

Abstract: Multi-step ADCs performs multi-step conversion by generating a residue for a subsequent stage to digitize. To generate a residue, a stage in the multi-step ADC would reconstruct the input signal to the stage using a feedforward digital to analog converter (DAC). Non-linearities in the DAC can directly affect the overall performance of the multi-step ADC. To reduce power consumption and complexity of analog circuit design, digital background calibration schemes are implemented to address the non-linearities. The non-linearities that the calibration schemes address can include reference, DAC, and quantization non-linearities.

Abstract: A sampling circuit comprises a switch circuit and a gate bootstrapping circuit. The switch circuit includes a switch input to receive an input voltage, a gate input, and a switch output. The gate bootstrapping circuit provides a boosted clock signal to the gate input of the switch circuit. The boosted voltage of the boosted clock signal tracks the input voltage by a voltage offset. The gate bootstrapping circuit includes a single boost capacitance coupled between a first circuit node and a second circuit node. A high supply voltage is applied to the first circuit node and the input voltage is applied the second circuit node to generate the boosted voltage on the single boost capacitance.

Abstract: Systems and methods for sensing angular motion using a microelectromechanical system (MEMS) gyroscope are described. These systems and methods may be useful for sensing angular motion in the presence of low-frequency noise, which may be noise below 1 KHz. In a system for sensing angular motion, low-frequency noise may give rise to duty cycle jitter, which may affect the demodulation of the sense signal and cause errors in angular motion estimates. The systems and methods described herein address this problem by relying on double-edge phase detection technique that involves sensing when the rising and falling edges of the resonator signal deviate from their expected values in the idealized 50% duty cycle scenario. To prevent the formation of ripples in the double-edge phase detection that may otherwise affect the demodulation of the sense signal, a switch may be used. The switch may be maintained in a non-conductive state when a ripple is received.

Abstract: Multiplying digital-to-analog converter (MDACs) are implemented in pipelined ADCs to generate an analog output being fed to a subsequent stage. A switched capacitor MDAC can be implemented by integrating a capacitor digital-to-analog converter (DAC) with charge pump gain circuitry. The capacitor DAC can implement the DAC functionality while the charge pump gain circuitry can implement subtraction and amplification. The resulting switched capacitor MDAC can leverage strengths of nanometer process technologies, i.e., very good switches and highly linear capacitors, to achieve practical pipelined ADCs. Moreover, the switched capacitor MDAC has many benefits over other approaches for implementing the MDAC.

Abstract: Systems and methods are disclosed for improved linearity performance of a mixer. An example mixer includes switching circuit elements configured to be switched on and switched off based at least partly on a local oscillator signal and capacitors including a respective capacitor in parallel with each of the switching elements. The mixer is configured to mix the input signal with the local oscillator signal to thereby frequency shift the input signal.

Abstract: A receiver system for an on-off key (“OOK”) isolator system may include a pair of receivers. A first receiver may generate a first current signal representing a received OOK signal, and a second receiver may generate a second current signal from a common mode representation of the received OOK signal. The receiver system may include circuitry to compare the first and second current signals and generate an output signal therefrom.

Abstract: A pipeline ADC architecture with suitable feedback can implement noise shaping. By feeding back the residue generated by the last residue generating stage to selected locations in the pipeline ADC, the delays in a pipeline ADC can create a finite impulse response (FIR) filtered version of the quantization error. The FIR filtered quantization error is added to the signal and evaluated by the pipeline ADC, which results in spectral shaping of the quantization noise. Unlike a conventional pipeline ADC, the output of the backend stage is scaled and filtered by a noise transfer function (NTF) of the residue generating stages prior to combining the output with other outputs of the pipeline ADC. The processing of the shaped quantization noise by the backend stage results in further noise suppression.

Abstract: An exemplary energy harvester includes a piezoelectric diaphragm, an eccentric mass that rotates in response to external motion, and a piezoelectric stress inducer coupled with the eccentric mass and the piezoelectric diaphragm. The piezoelectric stress inducer deforms the piezoelectric diaphragm in response to rotational motion of the eccentric mass, causing the piezoelectric diaphragm to generate electrical energy.

Abstract: An ADC can include a plurality of time-interleaved ADCs to increase the overall sampling rate of the ADC. Such an ADC can have interleaving errors, since the time-interleaved ADCs in the ADC are not always perfectly matched. One way to calibrate for these mismatches is by observing the digital output signals of the time-interleaved ADCs in the background, or more broadly, without knowledge of the input signal to the ADC (often referred to as “blind” calibration). Due to the nature of these calibrations, the performance of the calibration would significantly degrade when the input signal has certain problematic input conditions, such as a certain coherent input frequency. To address this issue, the data being used for calibration of interleaving errors can go through a qualifying process to assess whether to update error estimates based on the data.

Abstract: Techniques for self-testing of microelectromechanical systems (MEMS) inertial sensors are described. Some techniques involve testing inertial sensor characteristics such as an accelerometer's sensitivity to acceleration and a gyroscope's sensitivity to angular motion. The tests may be performed by providing a test signal, which simulates a stimulus such as an acceleration or angular rate, to a MEMS inertial sensor and examining the sensor's output. The efficacy of such self-tests may be impaired by spurious signals, which may be present in the sensor's environment and may influence the sensor's output. Accordingly, the self-testing techniques described herein involve detecting the presence of any such spurious signals and discarding self-test results when their presence is detected. In some embodiments, the presence of spurious signals may be detected using a signal obtained by mixing the response of the MEMS inertial sensor with a reference signal substantially in quadrature with the test signal.