Abstract: Class-D amplifiers have evolved from using binary pulse-width modulation (PWM) modulators to three-level PWM modulators. Three-level PWM drivers for audio applications offer the benefits of eliminating costly elements at the output of an audio system. However, they also introduce increased common-mode interference. Three-level PWM generates three states, but one state has two interchangeable representations which can be scrambled in order to shape the common-mode output spectrum.

Abstract: A method of rotating a digital image includes performing a first pass to process a selected image tile of a source image. The first pass includes copying a set of pixels of the selected image tile from a first memory to a processor memory, where the set of pixels comprises a portion of the selected image tile. The first pass further includes grouping the set of pixels into blocks of pixels and writing each of the blocks of pixels to a memory location. The method further includes repeating the first pass until each of the pixels of the selected image tile is processed, performing a second pass to process the blocks of pixels, and repeating the second pass until each of the blocks of pixels is processed. The second pass includes copying blocks of pixels, regrouping the blocks of pixels, and writing the regrouped pixels to a destination image location.

Abstract: A processor is provided that includes a primary memory and color conversion logic. The primary memory may store a first color look-up table (LUT) related to a second color space. The color conversion logic, in response to a received set of pixels having color values in a first color space, converts the received set of pixels to a second color space. The color conversion logic selectively accesses, based on a comparison of one or more pixel parameters to a threshold, one of the primary memory and a secondary memory located on a second device to obtain a color value of the second color space that is associated with each pixel of the set of pixels. The color conversion logic monitors the number of times that each of the primary memory and the secondary memory are accessed and automatically adjusts the threshold to maintain an access ratio.

Abstract: A system is described for encryption and decryption of digital data prior to the digital data entering the memory of a digital device by generating a key, sub-key and combining the sub-key with mixed digital data, where the encryption and decryption occurs between the memory controller and the input output register.

Abstract: A triangular waveform generator is converted to a free running oscillator controlled by a calibration code. The free running oscillator can be synchronized to an external clock signal by comparing the external clock frequency to the frequency of the triangular waveform and adjusting the calibration code until the discrepancy in frequency is minimized.

Abstract: Poly-phase filters are used to offer an efficient and low complexity solution to rate conversion. However, they suffer from inflexibility and are not easily reconfigured. A novel design for rate converters employ poly-phase filters but utilize interpolation between filter coefficients to add flexibility to rate conversion. This interpolation can be implemented as an interpolation of the poly-phase filter results. Additional approximations can be made to further reduce the amount of calculations required to implement a flexible rate converter.

Abstract: Systems and methods for providing bias currents to multiple analog circuits are disclosed. An integrated circuit comprises a calibration circuit which compares a high tolerance external component to a plurality of internal components manufactured to span the variability of the process, voltage and temperature. The best fitting internal component is communicated to bias circuits which can select an internal component from a local plurality of internal components with matching desired characteristics. In this manner, analog circuits can be locally biased with the tolerance usually associated with a high tolerance external reference component, without the necessity for a local external reference component.

Abstract: The invention relates to a demodulator circuit in a communication system using a multi-carrier modulation scheme. The demodulator uses channel state information for respective carriers in the multi-carrier modulation to de-map the received data.

Abstract: The disclosed methods of low power communications facilitate high speed reception of data from an access point (AP) with low transmission latencies while remaining in power save mode as long as possible. The disclosed methods allow the client to remain in a power save state and involve creating a synchronous client frame exchange with the AP that is independent of a digital traffic indication map and the AP's beacon interval. Two methods to accomplish this goal are disclosed: one which involves sending PS Poll Frames; and one that includes fast CAM switching, both at a self tuning frequency.

Abstract: A modem for use with a computer having a demodulator and a decoder, the modem comprises a hardware interface; a demodulator front-end having a first input and a first output, the first output of the demodulator front-end being configured to interface with the demodulator of the computer and to provide a demodulated front-end signal to the demodulator over the hardware interface; and a forward error correction (FEC) unit having a second input and a second output, the second input of the FEC unit being configured to interface with the demodulator of the computer and to receive a demodulated signal from the demodulator over the hardware interface, the demodulated signal being a demodulation of the demodulated front-end signal, and the second output of the FEC unit being configured to interface with the decoder of the computer and to provide an FEC signal to the decoder over the hardware interface.

Abstract: Class-D amplifiers have evolved from using binary pulse-width modulation (PWM) modulators to three-level PWM modulators. Three-level PWM drivers for audio applications offer the benefits of eliminating costly elements at the output of an audio system. However, they also introduce increased common-mode interference. Three-level PWM generates three states, but one state has two interchangeable representations which can be scrambled in order to shape the common-mode output spectrum.

Abstract: A raster to block converter and equivalently a block to raster converter can be implemented using enough memory to contain a single image band, that is a band of pixels of height equal to a single block but spanning the entire width of an image. The raster to block converter can operate at full rate so that as soon as a pixel is read out from the memory a new pixel can be stored in its place. The location of a pixel can be tracked using a mapping involving basic modular arithmetic. This raster to block converter is scalable so that it can work with any size image and block size.

Abstract: Laser printers are plagued with an assortment of alignment issues. In color laser printers the issues are exacerbated. Variations in distance from the mirror to the drum can lines in different color planes to vary in size. Variations in angles in the facets of the mirror can cause alignment issues between lines. Even lack of synchronization between the dot clock and start of line indication can cause misalignment between rows. In addition, a cosine distortion occurs due to the non-constant linear velocity of the laser scan of a single line. A very high speed master clock can drive the laser scanning unit. By using a very high speed clock, the control circuitry has the resolution to compensate for many of these distortion types, by appropriately counting clock cycles and indicating such to the laser modulator.

Abstract: Transformer driven by data modulated signal provides isolated power. Outbound data is extracted from the data modulated signal received from the transformer. Inbound data received in isolated circuitry modulates the load presented to transformer. Inbound data perceived in non-isolated circuitry by sensing load experienced by the transformer.

Abstract: A method of rotating a digital image includes performing a first pass to process a selected image tile of a source image. The first pass includes copying a set of pixels of the selected image tile from a first memory to a processor memory, where the set of pixels comprises a portion of the selected image tile. The first pass further includes grouping the set of pixels into blocks of pixels and writing each of the blocks of pixels to a memory location. The method further includes repeating the first pass until each of the pixels of the selected image tile is processed, performing a second pass to process the blocks of pixels, and repeating the second pass until each of the blocks of pixels is processed. The second pass includes copying blocks of pixels, regrouping the blocks of pixels, and writing the regrouped pixels to a destination image location.

Abstract: Audio transducers (headphones, speakers, microphones) inherently do not accurately reproduce the signal presented to them at the input. This can be compensated for by taking into account the transducer characteristics and transforming the input signal using a digital signal processor (DSP) to counteract the inaccuracies. However, for the compensation to take place, the DSP needs to know the characteristics of the transducer. For systems with built-in transducers (like laptops with internal speakers) the characteristics of the internal speakers can be stored on the hard-drive of the laptop and the DSP can read this data and make the appropriate compensations. Because a transducer (headphone, speaker, microphone) has its own characteristics that need to be compensated for separately, a profile is supplied to the DSP either by a database lookup based on an identification made by the user or transducer itself or by profile information stored on the transducer.

Abstract: Adequate heat dissipation is essential for semiconductor devices. When a device exceeds a specified junction temperature, the device can be damaged, not perform correctly, or can have a reduced operating life. Semiconductor packages must dissipate heat from the chip to the external environment (i.e. to the PCB, air, etc) to keep the semiconductor device below a certain temperature threshold. For most devices, the most efficient way to dissipate the heat is through the package external I/O connections and into the PCB that it is mounted to. For Ball Grid Array (BGA) packages, the external I/Os are solder balls. Variable pitch packages pose advantages in heat dissipation without introducing significant costs.

Abstract: Presently many audio chips suffer from pop issues, which is especially serious for single ended audio drivers. An audio pop is a disturbance in the output caused by a sudden transition of chip power, particularly when a chip is powered on or powered off. Furthermore, compensation networks included in the amplifiers on audio chips for stability offer a significant path for transmitting power disturbances to the output. Hence, circuitry is developed to suppress pops in the output stages of an amplifier.

Abstract: Poly-phase filters are used to offer an efficient and low complexity solution to rate conversion. However, they suffer from inflexibility and are not easily reconfigured. A novel design for rate converters employ poly-phase filters but utilize interpolation between filter coefficients to add flexibility to rate conversion. This interpolation can be implemented as an interpolation of the poly-phase filter results. Additional approximations can be made to further reduce the amount of calculations required to implement a flexible rate converter.

Abstract: Disclosed herein are embodiments of electrostatic discharge (ESD) protection circuits. In certain embodiments an ESD protection circuit may include two series resistor-capacitor (RC) circuits. One series RC circuit may have a short time constant and may selectively activate a current shunt between two power rails in response to an ESD event. Accordingly, the ESD circuit may be able to respond to fast ramping ESD events. The other series RC circuit has a longer time constant, and maintains the current shunt in an active state for a sufficient amount of time to allow the ESD event to be completely discharged.