Abstract: A method and apparatus for conserving power of a mixed-signal system-on-a-chip having analog circuitry, involving determination of an analog variation parameter that is representative of an integrated circuit fabrication process variance of the integrated circuit, and an operational temperature associated with the analog variation parameter. With the analog variation parameter and the operational temperature, an adjustment signal is determined for a power supply level of the integrated circuit, such that power consumption of the integrated circuit is optimized. Further, in mixed-signal integrated circuits with digital and analog circuitry, a digital variation parameter is determined, where the adjustment signal determination is based on the digital variation parameter and the analog variation parameter with respect to the operational temperature. With such a method and apparatus, power consumption is optimized on an IC-by-IC basis such that power consumption of each IC is optimized.

Abstract: A successive approximation Analog-to-Digital Converter (“ADC”) having a successive approximation controller operably coupled to convert a control signal into a digital output of the successive approximation ADC, a current-steered Digital-to-Analog Converter operably coupled to convert the digital output of the successive approximation ADC into an analog feedback signal, and a comparator module operably coupled to compare the analog feedback signal with an analog input of the successive approximation ADC to produce the control signal. A further aspect is a method for increasing accuracy for a digital successive approximation of an analog input signal. The method includes determining a signal characteristic of the analog input signal to an Analog-to-Digital Converter (“ADC”), and selecting a reference voltage source of a Digital-to-Analog Converter of the ADC from a plurality of reference voltage sources based on the analog input signal.

Abstract: A current threshold circuit includes a series impedance, a reference voltage source, and a comparison module. The series impedance couples an output of a current source to a load, wherein impedance of the series impedance is substantially less than impedance of the load. The reference voltage source is operably coupled to produce a reference voltage differential. The comparison module is operably coupled to compare the reference voltage differential with a differential voltage of the series impedance, wherein the comparison module generates an excessive current indication when the differential voltage of the series impedance compares unfavorably to the reference voltage differential.

Abstract: A controlled sampling module samples an input signal from an input device and a reference signal. The controlled sampling module includes a plurality of sample capacitors, a switching network, and a switch control module for controlling the switching network. The switching network couples a first capacitor of the plurality of capacitors to the reference signal during a first phase, and to the input signal during a second phase, such that a charge on the first capacitor remaining at an end of the first phase is cancelled during the second phase.

Abstract: A system and method for sensing the temperature of a device. This includes the establishment of a programmable current from an on-chip source, which in turn is used to produce a temperature dependent voltage from a temperature dependent resistive device. The temperature dependent resistive device is thermally coupled to a device for which the temperature is to be sensed. The temperature dependent voltage produced is converted to a digital value and equated to the temperature of the device.

Abstract: An amplifier circuit uses low threshold voltage devices for mid rail response in low voltage applications, but uses a high threshold voltage device at an output stage of the amplifier to generate an output from the amplifier.

Abstract: An overvoltage and backflow current protection circuit is employed when charging a battery. A switching circuit controls bias to the protection circuit to switch between overvoltage protection and backflow current protection.

Abstract: A system for digitally recording and time stamping an input audio signal during an audio event includes an input, an audio event detection module, a digital data recording and time-stamping module, and a memory. The input receives the input audio signal. The audio event detection module operably couples to the input and determines whether the input audio signal satisfies an audio event threshold. The digital data recording and time-stamping module operably couples to the input and to the audio event detection module and records and time stamps the input audio signal when the audio event detection module determines that the audio event is ongoing. The memory operably couples to the digital data recording and time-stamping module. The digital data recording and time-stamping module records the input audio signal in the memory.

Abstract: A system and method for sensing the temperature of a device. This includes the establishment of a programmable current from an on-chip source, which in turn is used to produce a temperature dependent voltage from a temperature dependent resistive device. The temperature dependent resistive device is thermally coupled to a device for which the temperature is to be sensed. The temperature dependent voltage produced is converted to a digital value and equated to the temperature of the device.

Abstract: A battery-optimized system-on-a-chip includes multimedia module, a high-speed interface, a processing module, on-chip memory, and an on-chip DC-to-DC converter. The multimedia module operably coupled to produce rendered output data from input data received via the high-speed interface and/or from data stored in the on-chip memory. The high-speed interface is operably coupled to provide data to and from an external source. The on-chip memory is operably coupled to store at least a portion of a multimedia application, wherein the processing module processes input multimedia data in accordance with the multimedia application to produce output multimedia data. The on-chip DC-to-DC converter is operably coupled to convert a battery voltage into a supply voltage that is provided to the multimedia module, the high-speed interface, the processing module, and/or the on-chip memory.

Abstract: Computationally efficient DTMF detection methods and apparatus are presented that meet all of the ITU recommendations using the modified non-uniform DFT. The system of the present invention employs a high band filter block and two low band filter blocks to detect power at the 8 DTMF tones. The frame length of the high band filter blocks is one half the length of the low band filter blocks. The frame lengths are chosen to meet the ITU frequency selectivity requirements for all DTMF frequencies. The frames of the two low band filter blocks are staggered to produce outputs alternately, and are aligned with respect to the frame of the high band filter block to produce low band filter block outputs that coincided with the high band filter block outputs without the need for signal buffering. A system of power level tests are employed in conjunction with a system of timing tests to ensure that all ITU timing and frequency constraints are met.

Abstract: A differential line driver that includes a 1st operational amplifier, a 2nd operational amplifier, an adjustable reference module, a 1st feedback impedance, and a 2nd feedback impedance. First inputs (e.g. the inverting input or non-inverting input) of the 1st and 2nd operational amplifiers are coupled to receive an input signal. The 2nd inputs (e.g. the compliment of the 1st input) of the 1st and 2nd operational amplifiers are operably coupled to receive an adjustable reference voltage from the adjustable reference module. The adjustable reference module provides the adjustable reference voltage based on the common mode of the power source for the 1st and 2nd operational amplifiers (e.g. Vdd, Vss) and/or the common mode of the input signal. The 1st and 2nd feedback impedances, (e.g. resistors) are coupled from the output of the respective operational amplifiers to either the 1st or 2nd input of the respective operational amplifiers.

Abstract: A differential line driver that includes a 1st operational amplifier, a 2nd operational amplifier, an adjustable reference module, a 1st feedback impedance, and a 2nd feedback impedance. First inputs (e.g. the inverting input or non-inverting input) of the 1st and 2nd operational amplifiers are coupled to receive an input signal. The 2nd inputs (e.g. the compliment of the 1st input) of the 1st and 2nd operational amplifiers are operably coupled to receive an adjustable reference voltage from the adjustable reference module. The adjustable reference module provides the adjustable reference voltage based on the common mode of the power source for the 1st and 2nd operational amplifiers (e.g. Vdd, Vss,) and/or the common mode of the input signal. The 1st and 2nd feedback impedances, (e.g. resistors) are coupled from the output of the respective operational amplifiers to either the 1st or 2nd input of the respective operational amplifiers.

Abstract: Computationally efficient DTMF detection methods and apparatus are presented that meet all of the ITU recommendations using the modified non-uniform DFT. The system of the present invention employs a high band filter block and two low band filter blocks to detect power at the 8 DTMF tones. The frame length of the high band filter blocks is one half the length of the low band filter blocks. The frame lengths are chosen to meet the ITU frequency selectivity requirements for all DTMF frequencies. The frames of the two low band filter blocks are staggered to produce outputs alternately, and are aligned with respect to the frame of the high band filter block to produce low band filter block outputs that coincided with the high band filter block outputs without the need for signal buffering. A system of power level tests are employed in conjunction with a system of timing tests to ensure that all ITU timing and frequency constraints are met.

Abstract: A line driver having variable impedance termination includes an impedance, a 1st variable feedback, a 2nd variable feedback, a summing module and a gain module. The 1st and 2nd variable feedbacks provide feedback based on the desired impedance for the particular application. The summing module is operably coupled to sum the 1st variable feedback, the 2nd variable feedback and a signal to produce a resultant signal. The gain module is operably coupled to receive the resultant signal and to amplify the signal to produce a gained signal. The output of the gain module is operably coupled to the impedance wherein the other node of the impedance provides the output of the line driver. To provide the feedback, the 1st variable feedback is operably coupled to the output of the gain module and the summing module and the 2nd variable feedback is operably coupled to the output of the line driver and the summing module.

Abstract: Computationally efficient DTMF detection methods and apparatus are presented that meet all of the ITU recommendations using the modified non-uniform DFT. The system of the present invention employs a high band filter block and two low band filter blocks to detect power at the 8 DTMF tones. The frame length of the high band filter blocks is one half the length of the low band filter blocks. The frame lengths are chosen to meet the ITU frequency selectivity requirements for all DTMF frequencies. The frames of the two low band filter blocks are staggered to produce outputs alternately, and are aligned with respect to the frame of the high band filter block to produce low band filter block outputs that coincided with the high band filter block outputs without the need for signal buffering. A system of power level tests are employed in conjunction with a system of timing tests to ensure that all ITU timing and frequency constraints are met.