Abstract: Circuitry for processing an analyte signal obtained from an electrochemical cell, the circuitry comprising: a converter, comprising: a first converter input configured to receive the analyte signal; a second converter input; and a converter output configured to output a converted analyte signal, the converter configured to generate the converted analyte signal in dependence on the analyte signal; a loop filter configured to filter a signal derived from the converted analyte signal to obtain a filtered analyte signal at a filter output; and a feedback path between the filter output and the second converter input.

Abstract: This application relates to modulator circuits for driving switching output stages in a class-D amplifier system or the like. The switching output stage has an output node and high-side and low-side switches for selectively connecting the output node to respective high-side and low-side voltages and is configured to be operable in a continuous conduction mode of operation, in which there is always an output current flowing throughout a switching cycle and also in a discontinuous conduction mode of operation where there is a period in each switching cycle where there is no output current. The modulator circuit comprises a compensator operable to apply compensation, in the discontinuous conduction mode of operation, to at least partly compensate for a non-linearity when operating in the discontinuous conduction mode.

Abstract: Circuitry for determining an impedance of an electrochemical cell comprising at least one first electrode and a second electrode, the circuitry comprising: drive circuitry configured to apply a stimulus to the electrochemical cell, the stimulus having a stimulation frequency and a stimulation amplitude; and measurement circuitry configured to: sample an output of the electrochemical cell at a sampling frequency to generate an output signal; determine an output amplitude of output signal at one or more alias frequencies, the one or more alias frequency based on the stimulation frequency and the sampling frequency; and determine the impedance of the cell at the stimulation frequency based on the output amplitude at the one or more alias frequencies and the stimulation amplitude; and control circuitry configured to: control the sampling frequency and the stimulation frequency such that a Nyquist rate of the sampling frequency is greater than stimulation frequency.

Abstract: Circuitry for a resistance of an electrochemical cell comprising at least one first electrode and a second electrode, the circuitry comprising: drive circuitry configured to apply a stimulus to the at least one first electrode of the electrochemical cell; sense circuitry configured to measure a response of the electrochemical cell to the stimulus, the response comprising a faradaic component and a non-faradaic component; and processing circuitry configured to: sample the response at a sample time, the sample time selected to maximise a ratio of the non-faradaic component to the faradaic component; and determine the resistance of the electrochemical cell based on the response at the sample time.

Abstract: A method of equalising a signal derived from an input device, the method comprising: receiving the signal; applying an order-statistic filter to the signal in the frequency domain to generate a statistically filtered signal; equalising the received signal based on the statistically filtered signal to generate an equalised signal.

Abstract: Circuitry for monitoring a characteristic of a battery cell integrated into a wearable device, the circuitry configured to: upon installation of the battery cell into the wearable device: obtaining a first signal from the battery cell; and upon activation of the wearable device after installation of the battery cell: obtain a second signal from the battery cell; and determine a characteristic of the battery cell based on the first signal and the second signal.

Abstract: An integrated circuit (IC) comprising: a digital interface terminal; and processing circuitry, wherein the IC is operable in: a first mode in which the digital interface terminal operates as a digital input or output terminal for communication with the integrated circuit; and a second mode in which the digital interface terminal operates as a hysteretic terminal for coupling with circuitry external to the IC to implement a hysteretic circuit.

Abstract: This application relates to methods and apparatus for outputting a modulated signal for driving a switching output stage. A modulator circuit includes a digital modulator that receives an input signal modified by a correction signal and outputs the modulated signal. A feedback node receives a feedback signal of the output of the switching output stage and a first filter receives and filters an inverted version of the modulated signal to generate a reference signal, such that the reference signal has gain and phase matching to the feedback signal. The reference signal and the feedback signal are both applied to a summation node to generate an analog correction signal which is input to an ADC. An error loop filter is configured to filter the ADC output to generate the digital correction signal.

Abstract: This application relates to methods and apparatus for switching drivers. The switching driver has first and second switches for selectively connecting an output node to first and second switching voltages respectively to generate a first output voltage. A compensator is configured to receive a first monitor signal indicative of a sum of the first and second switching voltages and a second monitor signal indicative of a difference between the first and second switching voltages and to apply compensation to the input signal based on the first and second monitor signals so as to compensate for variations in the first and second switching voltages from defined nominal values of the first and second switching voltages. A modulator controls a duty cycle of the first and second switches based on the input signal after said compensation has been applied.

Abstract: Circuitry for determining a characteristic of an electrochemical cell having a first electrode and a second electrode, the circuitry comprising: measurement circuitry configured to measure a sense current derived from the first electrode and output a sense signal at an output of the measurement circuitry based on the measured sense current; a filter configured to filter the sense signal to obtain a filtered sense signal; and processing circuitry configured to: estimate a signal noise level in the filtered sense signal; and determine the characteristic of the electrochemical cell based on the signal noise level.

Abstract: Circuitry for determining one or more characteristics of an electrochemical cell comprising a first working electrode and a counter electrode, the circuitry comprising: drive circuitry configured to apply a first stimulus to the first working electrode; measurement circuitry configured to measure a first response at the first working electrode; and processing circuitry configured to: applying compensation to the first response to obtain a first corrected response of the electrochemical cell to the first stimulus; and determine a first characteristic of the one or more characteristics of the electrochemical cell based on the first corrected response, the first characteristic associated with the first working electrode.

Abstract: Circuitry for measuring a characteristic of an electrochemical cell, the circuitry comprising: a comparator having a first comparator input, a second comparator input and a comparator output; a feedback path between the comparator output and the second comparator input configured to provide a feedback signal to the second comparator input; and a loop filter configured to apply filtering to the feedback path to generate the feedback signal, wherein the loop filter comprises the electrochemical cell.

Abstract: Switching transducer driver circuitry for driving a load, the switching transducer driver circuitry comprising: output stage circuitry comprising: a first output stage switch operable to couple the load to a first voltage supply; a second output stage switch operable to couple the load to a second voltage supply; and a third output stage switch operable to couple the load to a controllable third voltage supply, wherein a voltage level of the controllable third voltage supply is based on an input signal to the switching amplifier circuitry.

Abstract: Switching driver circuitry comprising: a first half-bridge configured to switch an output node of the switching driver circuitry between a first supply voltage having a first magnitude and a second supply voltage having a second magnitude that is lower than the first magnitude; a second half-bridge configured to switch the output node between a third supply voltage having a magnitude that is equal to or lower than the second magnitude and a fourth supply voltage having a fourth magnitude that is lower than the third magnitude; and an isolation switch coupled to the first and second half-bridges and operable to isolate the second half-bridge from the first half-bridge.

Abstract: Switching driver circuitry comprising: a first half-bridge configured to switch a first supply voltage having a first magnitude; a second half-bridge configured to switch a second supply voltage having a second magnitude, wherein the first magnitude is greater than the second magnitude; and an isolation switch coupled to the first and second half-bridges and operable to isolate the second half-bridge from the first half-bridge.

Abstract: Circuitry for determining a characteristic of an electrochemical cell having a first electrode and a second electrode, the circuitry comprising: a first capacitor node and a second capacitor node for coupling of a series capacitor therebetween, the first capacitor node for coupling to the working electrode; drive circuitry coupled to the second capacitor node, the drive circuitry configured to apply a first time-varying stimulus to the first electrode via the series capacitor; measurement circuitry configured to determine a sense signal derived from a sense current at the first electrode and output the sense signal at an output of the measurement circuitry; and processing circuitry configured to determine a characteristic of the electrochemical cell based on the sense signal.

Abstract: A method of processing subvocalized speech of a user, the method comprising: receiving an audio signal from an input transducer configured to capture speech of the user; receiving a first motion signal from a first motion sensor configured to detect motion of a jaw or a temporomandibular joint (TMJ) of the user; determining the presence of audible speech in the audio signal; when audible speech is present in the audio signal: correlating the audible speech with first motion data in the first motion signal to generate mapping data mapping the first motion data to the audible speech; when audible speech is not present in the audio signal: determining subvocalised speech of the user based on the first motion data and the mapping data.

Abstract: This application relates to methods and apparatus for compensating for distortion in an output drive signal of a switched-mode amplifier which arises from non-linearity of an inductor in an output path for the drive signal. A distortion predictor is configured to predict the distortion in the output drive signal. The distortion predictor has a current predictor configured to determine a predicted current in the inductor based on, at least, an indication of an input voltage for the inductor. A model then models the distortion based on the predicted current and a corrector determines a correction term based on the predicted distortion that can be additively applied to an input signal to at least partly compensate for the distortion in the drive signal.

Abstract: A microphone device, comprising: a microphone configured to generate an audio signal; a natural speech detection module for detecting natural speech in the first audio signal; wherein, on detection of the natural speech in the first audio signal, the natural speech detection module is configured to output a trigger signal to a speech processing module to process the natural speech in the audio signal.

Abstract: Circuitry for determining an impedance of an electrochemical cell comprising at least one first electrode and a second electrode, the circuitry comprising: drive circuitry configured to apply a stimulus to the electrochemical cell, the stimulus having a stimulation frequency and a stimulation amplitude; and measurement circuitry configured to: measure an output of the electrochemical cell to generate an output signal; separate the output signal into a linear component and a non-linear component; and determine the impedance of the cell based on the linear component of the response.