Abstract:
An example apparatus includes: a first switch having a control terminal; a second switch having a first terminal and a control terminal; detection circuitry having a first terminal and a second terminal the detection circuitry configured to detect a parasitic resistance at the first terminal of the second switch; and controller circuitry having a first terminal and a second terminal, the first terminal of the controller circuitry coupled to the control terminal of the first switch and the control terminal of the second switch, the second terminal of the controller circuitry coupled to second terminal of the detection circuitry, the controller circuitry configured to disable the first switch responsive to the detection of the parasitic resistance.
Abstract:
The disclosure provides a circuit for impedance measurement. The circuit includes an excitation source coupled between a first set of input switches. An impedance network is coupled between the first set of input switches and a first set of output switches. The impedance network includes a body impedance and a plurality of electrode impedances. A sense circuit is coupled to the first set of output switches. The sense circuit measures the body impedance and at least one electrode impedance of the plurality of electrode impedances.
Abstract:
An ECG signal acquisition system includes a first amplifier which has a non-inverting input adapted to be coupled to a first differential input, an inverting input adapted to be coupled to a second differential input, and an output. The system includes first and second biasing resistors coupled between the non-inverting and inverting inputs of the first amplifier. The system includes an average estimation circuit which has a first input coupled to the non-inverting input of the first amplifier and a second input coupled to the inverting input of the first amplifier. The system includes a driver amplifier which has an inverting input coupled to the output of the average estimation circuit, a non-inverting input coupled to receive a reference common-mode voltage, and an output. The system includes a low-pass filter coupled between the output of the driver amplifier and the biasing resistors.
Abstract:
A system may comprise: an excitation current source; a first electrode coupled to the excitation current source; and a second electrode coupled to the excitation current source. The first and second electrodes may be configured to pass an excitation current from the excitation current source through a human body. First and second calibration resistors may be coupled to and positioned between the excitation current source and the first electrode. Third and fourth calibration resistors may be coupled to and positioned between the excitation current source and the second electrode. The system may also comprise a sensor configured to measure voltages across each of the first, second, third, and fourth calibration resistors.
Abstract:
A bio-sensing device (and method) calibrates a time period used to make bio-physical measurements. The device initiates a light source sense phase followed by a first ambient sense phase and a second ambient sense phase. In the light source sense phase, the device is configured to receive a digital value indicative of current through a photodetector while the light source circuit is enabled and in each of the first and second ambient sense phases, the device is configured to receive digital values while the light source circuit is disabled. The device iteratively varies the time period between the phases until the digital value received during the first ambient sense phase is within a threshold of the digital value received during the second ambient sense phase. It then applies the same time separation between the light source sense phase and the ambient phase thereby equalizing the magnitude of the ambient light in the two phases.
Abstract:
At least some embodiments are directed to a light detection system comprising a photodiode, a transimpedance amplifier (TIA) having a differential output and a differential input coupled across the photodiode, a first bias current source coupled to an anode of the photodiode, and a second bias current source coupled to a cathode of the photodiode. The system also comprises a dynamic control logic coupled to the first and second bias current sources and configured to vary bias currents provided by the first and second bias current sources based on the differential output such that the photodiode is reverse-biased.
Abstract:
DC offset correction is provided with low frequency support. A first input terminal for receiving an input signal is selectively coupled to a resistance and a capacitor that are series coupled between the first input terminal and a corresponding output terminal. In a calibration phase, the series resistance is coupled between the input terminal and the capacitor and an average voltage level of the input is stored on capacitor. In a signal processing phase, the charged capacitor is coupled in series between the input terminal and the output terminal while the resistance is bypassed. The output signal obtained contains the high and low frequency components of the input signal, while the DC offset in the input signal is removed from the output signal. A differential circuit and methods are disclosed. Additional embodiments are disclosed.
Abstract:
An example apparatus includes: driver circuitry having a first terminal and a second terminal; and voltage control circuitry having a first terminal and a second terminal, the first terminal of the voltage control circuitry coupled to the first terminal of the driver circuitry, the second terminal of the voltage control circuitry coupled to the second terminal of the driver circuitry, the voltage control circuitry configured to supply an LED supply voltage.
Abstract:
Systems, apparatus, articles of manufacture, and methods are disclosed to detect a pace pulse in an electrocardiogram (ECG) signal. An example apparatus includes programmable circuitry configured to execute instructions to: identify a leading edge of a pulse in an input signal based on an amplitude change; identify a transition time of the leading edge of the pulse; validate the leading edge of the pulse based on the amplitude change and transition time; identify a trailing edge of the pulse; determine a width of the pulse between the leading edge and the trailing edge; and validate the pulse based on the width.
Abstract:
The disclosure provides a circuit for impedance measurement. The circuit includes an excitation source that generates an excitation signal. A switched resistor network is coupled to the excitation source, and generates an output signal in response to the excitation signal. A sense circuit is coupled to the switched resistor network, and generates a sense signal in response to the output signal. A comparator is coupled to the sense circuit, and generates a clock signal in response to the sense signal. A mixer is coupled to the sense circuit, and multiplies the sense signal and the clock signal to generate a rectified signal. A low pass filter is coupled to the mixer and filters the rectified signal to generate an averaged signal. A processor is coupled to the low pass filter and measures a body impedance from the averaged signal.