Texas Instruments Corporation

Ajit Sharma

Srinath Mathur Ramaswamy

Sriram Narayanan

Arup Polley

Seung Bae Lee

Keith Ryan Green

Rajni J Aggarwal

Kemal Safak Demirci

Wen Li

A CMOS integrated circuit includes a Hall sensor having a Hall plate formed in a first isolation layer which is formed concurrently with a second isolation layer under a MOS transistor. A first shallow well with a conductivity type opposite from the first isolation layer is formed over, and extending to, the Hall plate. The first shallow well is formed concurrently with a second shallow well under the MOS transistor. The Hall sensor may be a horizontal Hall sensor for sensing magnetic fields oriented perpendicular to the top surface of the substrate of the integrated circuit, or may be a vertical Hall sensor for sensing magnetic fields oriented parallel to the top surface of the substrate of the integrated circuit.

Hall sensor with buried hall plate

An LED (light-emitting diode) driver for a photoplethysmography system, including a switched-mode operational amplifier for driving a driver transistor with a source-drain path in series with the LED. In a first clock phase in which the LED is disconnected from the driver transistor, the amplifier is coupled in unity gain mode, and a sampling capacitor stores a voltage corresponding to the offset and flicker noise of the amplifier; the gate of the driver transistor is precharged to a reference voltage in this first clock phase. In a second clock phase, the sampled voltage at the capacitor is subtracted from the reference voltage applied to the amplifier input, so that the LED drive is adjusted according to the sampled noise. A signal from the transmitter channel is forwarded to a noise/ripple remover in the receiving channel, to remove transmitter noise from the received signal.

Transmitter architecture for photoplethysmography systems

An analog to digital converter (ADC) system that includes a first amplifier configured to amplify an analog input signal to produce an amplified direct current (DC) signal, an ADC configured to receive the amplified DC signal and convert the amplified DC signal into a digital DC signal, a digital to analog converter configured to receive the digital DC signal and convert the digital DC signal into an analog DC signal, and a second amplifier configured to receive an analog alternating current (AC) signal comprising the analog DC signal subtracted from the analog input signal and amplify the analog AC signal to produce an amplified AC signal. The ADC is further configured to receive the amplified AC signal and produce a digital AC signal. The second amplifier has a gain greater than a gain of the first amplifier.

Baseline compensation system

Construction of a hall-effect sensor in a buried isolation region

The circuitry of an optical receiver reduces the ambient DC component and the pleth DC component to leave a pleth signal with substantially only a pleth AC component. The circuitry also provides gain control and can provide transmit power control to change the range of the pleth AC component to occupy a desired input range of an analog-to-digital converter.

Optical receiver chain for components of a photoplethysmograph signal

Reduced noise and power with rapid settling time and increased performance in multi-modal analog multiplexed data acquisition systems. An example apparatus arrangement includes a circuit input configured to receive a plurality of analog input signals; an analog to digital converter circuit configured to output a digital representation of an analog voltage; a selection circuit configured to select one of the analog input signals received at the circuit input; a buffer coupled to receive the selected one of the analog input signals; a filter coupled to the buffer and configured to perform a high bandwidth sample operation and a low bandwidth sample operation and having a filter output, responsive to a control signal; and a sampling capacitor coupled to the filter to sample the filter output, and having an output coupled to the analog to digital converter. Methods and additional apparatus arrangements are disclosed.

Methods and apparatus for reducing noise, power and settling time in multi-modal analog multiplexed data acquisition systems

An optical system includes an optical illumination source, an optical receiver, a correlation determination circuit, and an ambient condition control circuit. The optical illumination source is configured to emit a light in the direction of a target object. The optical receiver is configured to receive a combined optical signal that includes an ambient light component combined with an interrogation component. The correlation determination circuit is configured to compare the combined optical signal with an ambient light signal to identify a correlation factor. The ambient condition control circuit is configured to compare the correlation factor to a low correlation threshold value and a high correlation threshold value, and, based on the correlation factor exceeding the low threshold value and being less than the high correlation threshold value, cancel the ambient light component from the combined optical signal to produce an interrogation signal including the interrogation component.

Exploiting constructive interference from ambient conditions

A multi-segment capacitive successive approximation analog to digital converter (SAR ADC) is calibrated by determining an error voltage for each of a plurality of most significant bit (MSB) capacitors in a first segment using a calibration DAC. The first segment is connected to the second segment by an attenuation capacitor. Each of the error voltages corresponding to the MSB capacitors is digitized to form a set of digitized error voltages. An error voltage for each of a plurality of less significant bit (LSB) capacitors in at least the second segment is calculated by summing the set of digitized error voltages to form a sum of error voltages (sum(e)) and assigning a percentage of sum(e) as the error voltage for each of the LSB capacitors, such that a mismatch in the attenuation capacitor is mitigated.

Mismatch correction of attenuation capacitor in a successive approximation register analog to digital converter

Described examples include low power analog front end circuits for sensing repeating signal waveforms, including a first sampling circuit to sample an input signal, an analog detector circuit to provide a detector output signal representing a feature of the input signal, a second sampling circuit to sample the detector output signal, and a control circuit to control a sample rate or other analog front end operating parameter at least partially according to the sampled detector output signal, and to selectively enable and disable the analog detector circuit at least partially according to a model representing an expected repeating waveform of the input signal.

Sensor with low power model based feature extractor

The silicon real estate required for the semiconductor fabrication of a calibrated capacitor-based successive approximation register (SAR) analog-to-digital converter (ADC) () is substantially reduced by using a number of shared capacitors (SC-SCs&#x2212;1) which are used as calibration capacitors when operating in a calibration mode and as bit capacitors when operating in a normal mode.

Calibrated SAR ADC having a reduced size

An analog-to-digital converter (ADC) includes a first comparator, a second comparator, and a decision timing comparison logic unit. The first comparator is configured to output a first output voltage and the second comparator is configured to output a second output voltage during a same binary algorithmic iteration of the ADC. The decision timing comparison logic unit is configured to identify a first polarity of the first output voltage and a second polarity of the second output voltage and, if the first polarity is equivalent to a second polarity, to insert at least one redundant capacitor for a next binary algorithmic iteration of the ADC.

Dual comparator-based error correction scheme for analog-to-digital converters

A mixed signal device includes an analog circuit and a digital circuit coupled to the analog circuit. The digital circuit includes a component that samples a signal at a sampling rate that is dynamically variable by the digital circuit based on the bandwidth of the incoming signal. The digital circuit is to automatically assert a signal to the analog circuit to change a bias current of the analog circuit based on a change to the sampling rate in the digital circuit.

Sampling rate based adaptive analog biasing

A circuit includes a first amplifier configured to amplify an input signal to generate an output signal. An offset sensor is configured to sense DC offset based on the output signal, where the offset sensor includes a second amplifier configured to generate an offset reduction signal for the first amplifier based on the sensed DC offset. A T-network in the circuit includes at least three resistors coupled to provide a feedback connection between the input signal and the output signal for the first amplifier and to receive the offset reduction signal to mitigate DC offset in the first amplifier. Since this method reduces the low-frequency component of the signal, it also shapes and reduces the flicker noise.

Growing community of inventors

Dallas, TX, United States of America

Ajit Sharma