Abstract: An analog signal processor (ASP) application-specific integrated circuit (ASIC) is disclosed. The ACIS can be used for remotely monitoring ECG signals of a subject that has reduced power consumption. In one aspect, the ASIC performs the functions of: ECG signal extraction with high resolution using ECG readout channel, feature extraction using a band-power extraction channel, adaptive sampling the ECG signals using an adaptive sampling analog-to-digital converter, and impedance monitoring for signal integrity using an impedance monitoring channel. These functions enable the development of wireless ECG monitoring systems that have significantly lower power consumption but are more efficient that predecessor systems. In one embodiment, the ASP ASIC consumes 30 ?W from a 2V supply with compression provided by adaptive sampling providing large reductions in power consumption of a wireless ECG monitoring system of which the ASP ASIC forms a part.

Abstract: A current generator is disclosed. An example current generator includes a plurality of current cells connected in parallel, each current cell being connected to a switch. The current generator further includes a first summer configured to sum the output of each current cell of a first subset of the plurality of current cells and a second summer configured to sum the output of each current cell of a second subset of the plurality of current cells. The current generator also includes a combiner configured to combine the outputs of the first and second summers. Further, each switch is switchable according to a sequence to generate a summed output of the current cells at a plurality of quantization levels to generate positive and/or negative alternations of a pseudo-sinusoidal, alternating current.

Abstract: A method and apparatus is disclosed for adaptively sampling an analogue signal to increase the sampling rate in the presence of high frequency content within the signal, for example, QRS complex of an ECG signal. In one aspect, a change in a derivative of the analogue signal is used to control a voltage-controlled oscillator to provide a clock signal for an analogue-to-digital converter. The change in the derivative is compared to an automatically controlled threshold value. The clock signal controls the sampling rate of the analogue-to-digital converter so that the sampling rate is increased from one level, where only P and T waves are present to another higher level when the QRS complex has been detected.

Abstract: The present invention relates to a large time constant steering circuit for slowly changing a voltage on a node between at least two discrete voltage levels. The present invention further relates to a slow steering current DAC comprising said large time constant steering circuit. The present invention further relates to an instrumentation amplifier device comprising a current balancing instrumentation amplifier for amplifying an input signal to an amplified output signal and a DC servo-loop for removing a DC-component from the input signal. The present invention further relates to an EEG acquisition ASIC comprising said instrumentation amplifier device.

Abstract: A method and device is disclosed for continuously and simultaneously measuring an impedance signal and a biopotential signal on a biological subject's skin. In one aspect, the method includes attaching input and output electrodes to the biological subject's skin and applying a predetermined alternating current having a first frequency to the output electrodes for creating an alternating voltage signal over the input electrodes. The first frequency is above a predetermined minimum frequency. The method also includes measuring an input signal from the input electrodes which includes a biopotential signal and the alternating voltage signal. The method also includes extracting from the input signal the biopotential signal and the alternating voltage signal, and determining the impedance signal from the alternating voltage signal. The alternating voltage signal is extracted by amplifying and demodulating the input signal using a control signal having a frequency equal to the first frequency.

Abstract: A multi-channel biopotential signal acquisition system is disclosed. In the system, a plurality of biopotential channels is corrected for common-mode interference. In one aspect, each biopotential channel includes an electrode for providing a biopotential input signal and an associated amplifier for amplifying the biopotential input signal and providing a biopotential output signal. The output signal is processed in a processor. Each biopotential output signal is passed to a common-mode feedback system, which determines an average common-mode signal and feeds that signal back to each of the amplifiers in each of the biopotential channels to enhance common-mode rejection ratio of the system.

Abstract: The present invention relates to a large time constant steering circuit for slowly changing a voltage on a node between at least two discrete voltage levels. The present invention further relates to a slow steering current DAC comprising said large time constant steering circuit. The present invention further relates to an instrumentation amplifier device comprising a current balancing instrumentation amplifier for amplifying an input signal to an amplified output signal and a DC servo-loop for removing a DC-component from the input signal. The present invention further relates to an EEG acquisition ASIC comprising said instrumentation amplifier device.

Abstract: An analogue signal processor (ASP) application-specific integrated circuit (ASIC) is disclosed. The ACIS can be used for remotely monitoring ECG signals of a subject that has reduced power consumption. In one aspect, the ASIC performs the functions of: ECG signal extraction with high resolution using ECG readout channel, feature extraction using a band-power extraction channel, adaptive sampling the ECG signals using an adaptive sampling analogue-to-digital converter, and impedance monitoring for signal integrity using an impedance monitoring channel. These functions enable the development of wireless ECG monitoring systems that have significantly lower power consumption but are more efficient that predecessor systems. In one embodiment, the ASP ASIC consumes 30 ?W from a 2V supply with compression provided by adaptive sampling providing large reductions in power consumption of a wireless ECG monitoring system of which the ASP ASIC forms a part.

Abstract: The present invention relates to a large time constant steering circuit for slowly changing a voltage on a node between at least two discrete voltage levels. The present invention further relates to a slow steering current DAC comprising said large time constant steering circuit. The present invention further relates to an instrumentation amplifier device comprising a current balancing instrumentation amplifier for amplifying an input signal to an amplified output signal and a DC servo-loop for removing a DC-component from the input signal. The present invention further relates to an EEG acquisition ASIC comprising said instrumentation amplifier device.

Abstract: A method and apparatus is disclosed for adaptively sampling an analogue signal to increase the sampling rate in the presence of high frequency content within the signal, for example, QRS complex of an ECG signal. In one aspect, a change in a derivative of the analogue signal is used to control a voltage-controlled oscillator to provide a clock signal for an analogue-to-digital converter. The change in the derivative is compared to an automatically controlled threshold value. The clock signal controls the sampling rate of the analogue-to-digital converter so that the sampling rate is increased from one level, where only P and T waves are present to another higher level when the QRS complex has been detected.

Abstract: A method and device is disclosed for continuously and simultaneously measuring an impedance signal and a biopotential signal on a biological subject's skin. In one aspect, the method includes attaching input and output electrodes to the biological subject's skin and applying a predetermined alternating current having a first frequency to the output electrodes for creating an alternating voltage signal over the input electrodes. The first frequency is above a predetermined minimum frequency. The method also includes measuring an input signal from the input electrodes which includes a biopotential signal and the alternating voltage signal. The method also includes extracting from the input signal the biopotential signal and the alternating voltage signal, and determining the impedance signal from the alternating voltage signal. The alternating voltage signal is extracted by amplifying and demodulating the input signal using a control signal having a frequency equal to the first frequency.

Abstract: The present invention relates to a large time constant steering circuit for slowly changing a voltage on a node between at least two discrete voltage levels. The present invention further relates to a slow steering current DAC comprising said large time constant steering circuit. The present invention further relates to an instrumentation amplifier device comprising a current balancing instrumentation amplifier for amplifying an input signal to an amplified output signal and a DC servo-loop for removing a DC-component from the input signal. The present invention further relates to an EEG acquisition ASIC comprising said instrumentation amplifier device.