Abstract: This application relates to controlling a switching amplifier to drive a load with a differential drive signal. A controller is configured to control the switching amplifier to selectively operate in at least a first mode or a second mode, wherein in each mode, driver output nodes are modulated between switching voltages with a controlled duty-cycle and at least one of the switching voltages is different in the different modes. In the first mode, a common-mode voltage applied to the first and second output nodes has a first steady-state value and in the second mode a common-mode voltage applied to the first and second output nodes has a second, different. steady-state value. For a change in mode, the controller operates in a transitional period in which the common-mode voltage is ramped over time to reduce or eliminate any step change in common-mode voltage on the change in mode.

Abstract: This application relates to methods and apparatus for controlling a switching amplifier to drive a load with a differential drive signal based on an input signal. A controller controls the switching amplifier to selectively operate in at least a first or second modes based on the input signal, wherein in each mode, output nodes are modulated between switching voltages with a controlled duty-cycle and at least one of the switching voltages is different in the different modes. In steady-state operation in the first mode a common-mode voltage applied to the first and second output nodes has a first value and in steady-state operation in the second mode a common-mode voltage applied to the first and second output nodes has a second value, different to the first value; wherein at least one of first values and the second values is not equal to a voltage which is halfway between the switching voltages used in that mode.

Abstract: This application relates to methods and apparatus for controlling a switching amplifier to drive a load with a differential drive signal based on an input signal. A controller is configured to control the switching amplifier to operate in at least a first mode of operation in which the first and second output nodes of the switching amplifier are selectively modulated between first and second switching voltages with respective controlled duty-cycles. The controller controls the duty-cycle so as to controllably vary a common-mode voltage applied to the first and second output nodes in operation in the first mode. The controller comprises a first control loop for controlling the common-mode voltage and a second control loop for controlling the differential drive signal.

Abstract: This application relates to methods and apparatus for controlling a switching amplifier to drive a load with a differential drive signal based on an input signal. A controller is configured to control the switching amplifier to selectively operate in at least a first mode or a second mode based on the input signal, where, in the first mode, the output nodes are selectively connected to first and second switching voltages with a controlled duty-cycle, and in the second mode the output nodes are selectively connected to the first switching voltage and a third switching voltage with a controlled duty-cycle, where the third switching voltage is an intermediate voltage between the first and second switching voltages. The controller is configured to selectively increase an output resistance of the switching amplifier during a damping period which, at least partly, follows a change in mode.

Abstract: This application relates to methods and apparatus for switching amplifiers for driving a load. A switching amplifier is described which has first and second amplifier signal paths, for modulating respective first and second output nodes between switching voltages, so as to generate a differential drive signal across a load, where the load is connected between the first and second output nodes by respective first and second output paths. The switching amplifier is operable such that a common-mode voltage applied to the first and second output nodes may be controllably varied in use. The switching amplifier has at least one compensator configured to apply compensation to at least one of the first and second amplifier signal paths to compensate for any mismatch in transfer function of the first and second output paths.

Abstract: There is described a two-terminal multi-level memristor element synthesised from binary memristors, which is configured to implement a variable resistance based on unary or binary code words. There is further described a circuit such as a synapse circuit implemented using a multi-level memristor element.

Abstract: This application relates to an amplifier selectively operable in first or second modes. The first mode is a BTL mode with first and second output drivers (103p, 103n) both active to generate respective driving signals that vary with an input signal. The second mode is an SE mode, where the first output driver (103p) is active to generate a driving signal at and the output of the second driver (103n) is held constant. A controller (201) selectively controls the mode based on an indication of output signal amplitude. In the first mode, a ratio of magnitude of the two driving signals varies with the indication of output signal amplitude, i.e. the magnitudes of the two driving signals may vary so as to be not equal.

Abstract: Circuitry for processing an analyte signal obtained from an electrochemical cell, the circuitry comprising: a first analog-to-digital converter (ADC) configured to generate a first digital output based on the analyte signal; a second ADC configured to generate a second digital output based on the analyte signal; and control circuitry configured to control generation of the second digital output by the second ADC based on the first digital output from the first ADC.

Abstract: This application relates to methods and apparatus for sensing using controlled oscillators. A sensor apparatus has a first ring oscillator formed a plurality of delay elements which generates a first oscillator signal. At least one of the delay elements is a sensing delay element which includes a sensor component with an electrical property that varies with a measurand of interest to vary a propagation delay of the sensing delay element, and hence an oscillation frequency of the first oscillator signal.

Abstract: The present application relates to voltage-controlled oscillators (VCOs), in particular to VCOs suitable for implementation in compound semiconductor material and to the use of such VCOs. The VCO has an input node for receiving an input control voltage and an odd plurality of delay elements connected in a ring arrangement. Each delay element is connected between first and second defined voltages and comprises a depletion mode high-electron mobility transistor connected between the first defined voltage and an output of the delay element. The gate of the depletion mode high-electron mobility transistor is driven by the input control voltage and the gate of the enhancement mode high-electron mobility transistor is driven by the output of a preceding delay element.

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.