Maxim Integrated Products, Inc.

Qualcomm Technologies, Inc.

Nxp B.v.

Qualcomm Incorporated

Infineon Technologies Canada Inc.

Ashutosh Ravindra Joharapurkar

Patrick Yin Chan

Natarajan Viswanathan

Jean CauXuan Le

Arvind Sherigar

David L Allen

Abhishek Jain

Sung Ung Kwak

Zhemin Zhang

Rajesh Tiruvuru

Yalong Li

Ramesh G Karpur

Rohan Samsi

Sounak Maji

Samiran Dam

Karthikeya Kodur

Venugopal Reddy

Suraj Somashekara Kumar

Ashutosh Kumar

A circuit that is capable of generating a negative voltage on a negative voltage supply node. The circuit includes a negative voltage generation circuit, an oscillator and an oscillator control signal generator. The negative voltage generation circuit generates a negative voltage on the negative voltage supply node in response to receiving a signal from the oscillator. The negative voltage generated by the negative voltage generation circuit depends upon the frequency of the signal from the oscillator. The oscillator control signal generator controls the frequency of the signal from the oscillator by sensing the negative voltage present on the negative voltage supply node, and by increasing or decreasing the frequency of the signal from the oscillator accordingly. Thus, charge is replenished to the negative voltage supply node to more closely match the drawing of charge from that negative voltage supply node, thereby more accurately generating the negative voltage.

Negative voltage generator

A system for controlling an inductor current of a boost converter includes a start-up controller that is configured to generate a control signal that has a fixed on-time duration and a dynamic off-time duration that decreases with each cycle of the control signal, and a pulse width modulation (PWM) circuit that is configured to generate a PWM signal. During a start-up of the boost converter, the PWM signal transitions from a deactivated state to an activated state when the control signal is activated, and from an activated state to a deactivated state when the inductor current is equal to a reference current. The reference current corresponds to a peak value of the inductor current during the start-up. Thus, during the start-up, the duty cycle of the PWM signal increases with each cycle of the PWM signal. The PWM signal is provided to the boost converter for controlling the inductor current.

System for controlling inductor current of boost converter

An audio system has an amplifier having first and second power stages configurable to drive a speaker, each power stage having two transistors connected in series. Each of one or more analog-to-digital converters is connected to measure a corresponding voltage drop across a corresponding transistor. A processor is connected to characterize the operation of the audio system based on the measured voltage drops. The ADC(s) and the processor can be used during start-up and/or run-time operations of the audio system to determine or detect transistor ON resistance, system lag time, speaker current, open-load faults, shorted-load faults, and short-to-Vdd/Vss faults. To avoid errors, the processor determines or detects and avoids under-drive conditions, high-frequency conditions, ripple-current periods, and lag-time periods while characterizing the system operations.

Load diagnostics for audio amplifiers

Security devices for protecting ICs from backside security attacks. A security device includes an N&#x2212; well formed in a substrate, a P+ center disposed in the central region of the N&#x2212; well, and a P+ ring surrounding the N&#x2212; well. To prevent latchup, a pair of inner and outer N+ rings is formed in the N&#x2212; well. When a current source is applied to the P+ center, the current flows through a portion of the substrate and is picked up by the P+ ring. When an attacker mills the substrate or makes a trench in the substrate, the resistance of the substrate changes. By monitoring the voltage difference between the P+ center and P+ ring, the attempt to attack the die can be detected.

Detecting and thwarting backside attacks on secured systems

A differential sensing scheme provides a means for detecting one or more touch events on a touch sensitive device in the presence of incident noise. Instead of sensing one touch sensitive channel, such as a row, column, or single touch sensor, multiple touch sensitive channels are sampled at a time. By sampling two nearby channels simultaneously and doing the measurement differentially, noise common to both channels is cancelled. The differential sensing scheme is implemented using simple switch-capacitor AFE circuitry. The originally sensed data on each individual channel is recovered free of common-mode noise. The recovered sensed data is used to determine the presence of one or more touch events and if present the location of each touch event on the touch sensitive device.

Noise cancellation technique for capacitive touchscreen controller using differential sensing

Random sampling techniques include techniques for reducing or eliminating errors in the output of capacitive sensor arrays such as touch panels. The channels of the touch panel are periodically sampled to determine the presence of one or more touch events. Each channel is individually sampled in a round robin fashion, referred to as a sampling cycle. During each sampling cycle, all channels are sampled once. Multiple sampling cycles are performed such that each channel is sampled multiple times. Random sampling techniques are used to sample each of the channels. One random sampling technique randomizes a starting channel in each sampling cycle. Another random sampling technique randomizes the selection of all channels in each sampling cycle. Yet another random sampling technique randomizes the sampling cycle delay period between each sampling cycle. Still another random sampling technique randomizes the channel delay period between sampling each channel.

Use of random sampling technique to reduce finger-coupled noise

A capacitive touch panel includes sense electrodes arranged next to one another and drive electrodes arranged next to one another across the sense electrodes. The drive electrodes and the sense electrodes define a coordinate system where each coordinate location comprises a capacitor formed at a junction between one of the drive electrodes and one of the sense electrodes via mutual capacitance between the electrodes. The drive electrodes are configured to receive a first signal from a driver coupled with the drive electrodes for powering the drive electrodes to sense passive input to the capacitive touch panel at each coordinate location. Passive input can also be sensed via self-capacitance of the capacitive touch panel sensors. The drive electrodes and the sense electrodes are configured to receive a second signal from an active stylus to sense active input to the capacitive touch panel at each coordinate location.

Capacitive touch panel configured to sense both active and passive input with a single sensor

A touchscreen system for increasing the dynamic range of the system comprising a touchscreen coupled to an offset cancellation element and a capacitance measuring element. The offset cancellation element is configured to be dynamically changed in capacitance such that it offsets parasitic and sensor capacitances of the touchscreen sensors thereby leaving only touch event capacitance to be measured by the measuring element. The offset cancellation element is able to adjust to the initial unwanted capacitances of each sensor as well as dynamically adjust to changes in the unwanted capacitance due to the environment. In some embodiments, the offset cancellation element is a capacitance digital-to-analog converter that is controlled by a controller for offsetting the unwanted capacitance. As a result, the touchscreen system is able to utilize a small integrating capacitor thereby lowering cost and improving the dynamic range of the system.

Method and apparatus for improving dynamic range of a touchscreen controller

A touchscreen controller system determines the actual locations of multiple simultaneous touches by eliminating mutual capacitance between adjacent rows and columns during self-capacitance measurements and selectively enabling mutual capacitance during mutual capacitance measurements. During the self-capacitance measurements, the controller system generates a set of candidate touch locations, which includes the locations of real and ghost touches. During the mutual capacitance measurements, only the locations in the candidate set are measured and, from these measurements, the actual touch locations are determined. By limiting the mutual capacitive measurements to only a small subset of the locations over the entire touch panel, real touch locations are determined on a linear order. Also, by using on-chip integration capacitors, embodiments of the invention are able to perform each measurement in a single cycle.

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Bengaluru, India

Ashutosh Ravindra Joharapurkar