Texas Instruments Corporation

Milind Anil Borkar

Fernando Alberto Mujica

Chenchi Luo

Arthur John Redfern

Lei Ding

Roland Sperlich

Lars Risbo

William Louis Abbott

Zigang Yang

Gregory Copeland

Hardik Prakash Gandhi

Lars Jorgensen

Seydou Nourou Ba

Carson Arthur Wick

Theis Buchwald Christiansen

For protecting a speaker, an input signal is received, and an excursion of the speaker that would be caused by the input signal is predicted. In response to the predicted excursion exceeding a threshold, a targeted excursion of the speaker is determined by compressing the predicted excursion. The targeted excursion is translated into an output signal, which is output to the speaker.

Method and system for excursion protection of a speaker

An embodiment of the invention provides a method of creating a statistical model of a baseline capacitance Cof a capacitive sensor located on a capacitive-touch screen. A sensed capacitance Cof a capacitive sensor is measured during a particular state of the electronic device that includes the capacitive-touch screen. When physical contact is not made with the capacitive sensor, the sensed capacitance Cis stored as a baseline capacitance C. The baseline capacitance Cis then used to create the statistical model for that particular state of the electronic device. When physical contact is made with the capacitive sensor, the value of the baseline capacitance Cof the capacitive sensor is subtracted from the value of the sensed capacitance Cand the result, C=(C&#x2212;C), is sent to a touch detection circuit.

Baseline capacitance calibration

For protecting a speaker, an input signal is received and filtered into component signals. A sum of the component signals is approximately equal to the input signal. The component signals include at least first and second component signals. A perceived loudness to a human from the speaker is more sensitive to the first component signal than to the second component signal. A temperature of the speaker is estimated. In response to the estimated temperature, the second component signal is scaled. An output signal is output to the speaker in response to the first component signal and the scaled second component signal.

Method and system for temperature protection of a speaker

In an embodiment of the invention, the voice coil of an electro dynamic transducer is protected against thermal overload by estimating the temperature of a magnet in the electro dynamic transducer. When a power limit based on the temperature of the magnet and on a predetermined voice coil temperature limit is reached by an audio signal, the power applied to the voice coil is reduced.

Thermal control of voice coils in loudspeakers

An embodiment of the invention provides a method of detecting the position(s) where sensor(s) are activated on an interactive screen using sparse-activation compressive sensing. Sparse-activation compressive sensing makes use of the situation where the number of simultaneously activated sensors is substantially smaller than the number of sensors (nodes). Because the number of simultaneously activated sensors is substantially smaller than the number of sensors, the number of measurements required for determining which sensors are activated may also be reduced. Because fewer measurements are required when compared with full-scan techniques, less circuitry and power is required to detect the location(s) of activated sensors on an interactive screen.

System and method for sparse touch sensing on capacitive touch screen

Systems and methods for identifying a transmission channel response and a feedback channel response from a plurality of composite system responses are disclosed. A plurality of shifted feedback signals are created by shifting a feedback signal frequency by a plurality of first offset values and/or by shifting a transmission signal frequency by a plurality of second offset values. The feedback signals are compared to an input signal to identify the transmission channel response and/or a feedback channel response. A control signal is generated for a pre-distortion circuit to modify the input signal by an inverse of the transmission channel response. The composite system response is measured at a plurality of operating frequencies and at the plurality of offset values. The measurements are stored in a matrix and singular value decomposition is applied to the matrix of measurements to calculate the transmission channel response and feedback channel response.

System and method for estimating a transmit channel response and/or a feedback channel response using frequency shifting

An apparatus is provided. In the apparatus, an input to index (I2I) module maps a complex input into a real signal. A real data tap delay line is coupled to the I2I module and includes N delay-elements. A complex data tap delay line is configured to receive the complex input and includes M delay elements. A set of K of non-linear function modules is also provided. Each non-linear function module from the set has at least one real input, at least one complex input, and at least one complex output. A configurable connectivity crossbar multiplexer couples K of the N real tap delay line elements to real inputs of the set non-linear functions and couples K of the M complex tap delay line elements to complex inputs of the set non-linear function modules.

Systems and methods of power amplifier digital pre-distortion

A circuit for use with an amplification circuit having a predistortion datapath portion, a power amplifier portion and a gain portion. The predistortion datapath portion can output a predistorted signal based on the input signal. The power amplifier portion can output an amplified signal based on the predistorted signal. The gain portion can output a gain output signal based on the amplified signal. The circuit comprises a digital predistortion adaptation portion and a combiner. The digital predistortion adaptation portion can output a predistortion adaptation portion output signal. The combiner can output an error signal. The predistortion adaptation portion output signal is based on the input signal, the gain output signal and the error signal. The error signal is based on the difference between the predistorted signal and the predistortion adaptation portion output signal.

System and method for training pre-inverse of nonlinear system

A method of determining indices for matrix codewords in a matrix codeword codebook. The matrix codewords are adapted for communicating information between a transmitter and a receiver. The method includes retrieving from temporary storage, an eigenmode representation for a communications channel, where the eigenmode representation is based upon on a received signal precoded by a first matrix codeword. The method also includes performing a test on multiple vector codewords to identify a first vector codeword among the multiple vector codewords, where the test includes determining a relationship between the first vector codeword and the representation of an eigenmode. The first vector codeword is associated with a first vector codeword index that identifies the first vector codeword. The method also includes generating a matrix codeword index associated with a second matrix codeword in the matrix codeword codebook. The matrix codeword index is based upon the first vector codeword index, and the order of the first vector codeword is different from the order of the second matrix codeword.

Low complexity precoding matrix selection

A method of determining indicators for matrix codewords in a matrix codeword codebook, where the matrix codewords are adapted for communicating information between a transmitter and a receiver. The method includes providing a lookup table that is associated with multiple codewords that are associated with a codebook. The lookup table has m rows, and each row in the lookup table has a one-to-one correspondence with a codeword in the multiple codewords. Each row has p entries and each of the p entries holds a codeword indicator that identifies a codeword in the multiple codewords. The (i,j)entry in the lookup table holds the codeword indicator identifying the jmost similar codeword to the codeword associated with the irow according to a similarity metric, where 1&#x2266;i&#x2266;m and 1&#x2266;j&#x2266;p, and the m rows include a row k. The method includes identifying a first indicator in the row k by testing each of the indicators in the first p entries of row k to determine which of the indicators in the first n entries identifies a reduced search codeword that best satisfies a selection criterion, wherein, n has a predetermined value and 1&#x2266;n&#x2266;p, and, in relation to the other remaining indicators in the first n entries of the first row, the first indicator identifies the reduced search codeword that best satisfies the selection criterion.

Reduced search space technique for codeword selection

An apparatus is provided to determine pre-distortion for a nonlinear system. The apparatus comprises a datapath and a power amplifier. The datapath employs predistortion data to generally linearized the power amplifier. To generate this predistortion data, an indirect learning circuit and a direct learning circuit can be employed. The indirect learning circuit is generally coupled to the amplifier circuit so that it can iteratively adjust predistortion data during an indirect learning mode until convergence is reached. The direct learning circuit is generally coupled to the amplifier circuit and the indirect learning circuit and that receives the input signal so that the predistortion data can be copied to the direct learning circuit from the indirect learning after convergence is reached and so that the direct learning circuit can adjust the predistortion data during a direct learning mode.

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Dallas, TX, United States of America

Milind Anil Borkar