Integrated Device Technology, Inc.

Ambiq Micro, Inc.

Freescale Semiconductor,inc.

Ajaykumar A Kanji

Scott McLean Hanson

Jeffrey Blackburn

Kenneth Gozie Ifesinachukwu

An improved reference current generator for use in an integrated circuit. A voltage difference generator generates two voltages that are separated by a relatively small electrical potential. The two closely separated voltages are applied across a resistive element with relatively large impedance value resulting in a small and stable reference current. The stable reference current is mirrored and, if desired, amplified for use on the integrated circuit. A driver selectively drives state information off chip for assisting in post-silicon correction of unwanted sensitivities. A configuration memory stores values used to adjust effective device widths and lengths for correcting unwanted sensitivities.

Low power tunable reference current generator

A method and apparatus for generating an improved reference voltage for use, for example, in a system requiring accurate low power operation. In particular, our reference voltage generator is adapted to output VREF as a function of the voltage difference between V1 and V2. The reference voltage generator is further adapted to include our reference voltage tuner to compensate for predetermined sensitivities of the reference voltage VREF, and to adjust the absolute value of VREF. During manufacturing and system test, a driver may be used to drive a buffered or unbuffered version of VREF to off-chip test functionality. Also, a configuration memory may be used to store the trim settings during normal operation, and make such settings available to outside resources.

Low power tunable reference voltage generator

An audio output circuit includes a port attenuation circuit, which is configured to convert an abrupt dc voltage offset transition between a pair of audio signals received in sequence at an input thereof into a more gradual transition. This conversion is achieved by performing, in sequence, a ramp-to-mute operation on a first of the pair of audio signals and a ramp-from-mute operation on a second of the pair of audio signals. The ramp-to-mute operation includes ramping an output of the audio output circuit from a dc voltage offset associated with the first of the pair of audio signals to a reference dc voltage offset. The ramp-from-mute operation includes ramping the output of the audio output circuit from the reference dc voltage offset to a dc voltage offset associated with the second of the pair of audio signals. These ramping operations may be performed using voltage steps having uniform step size.

Audio output circuits having ramped attenuation circuits that inhibit pop disturbances when audio sources are switched

A plug-in device detection module includes a measurement signal generator for generating a measurement signal. A port coupler couples the measurement signal to a selected plug-in receptor of a plurality of plug-in receptors, generates an input/output signal and generates a port signal in response to the measurement signal. A reference signal generator generates a reference signal based on the input/output signal, the reference signal having a plurality of reference signal values. A detection module detects a plug-in device type of a plug-in device coupled to the selected plug-in receptor, based on the reference signal and the port signal.

Audio input-output module, plug-in device detection module and methods for use therewith

An audio output driver includes an audio amplifier for generating an amplified signal. A virtual ground generator generates a virtual ground signal in response to a virtual ground reference. A combiner produces an output signal, based on the amplified signal and the virtual ground signal, that is coupled to an audio output device. A voltage equalizer equalizes the virtual ground reference and the output signal when the supply voltage compares unfavorably to a supply voltage threshold.

Audio output driver and methods for use therewith

A plug-in detection module includes an impedance network for producing a plug-in signal in response to a supply signal that varies when one of a plurality of plug-in receptors is coupled to a plug connector and when one of the plurality of plug-in receptors is decoupled. A reference signal generator generates a reference signal having a plurality of reference signal values. A comparator generates a detection signal when the plug-in signal compares favorably to the reference signal. A processing module detects which of the plurality of plug-in receptors have a plug connector coupled thereto.

Audio input-output module, plug-in detection module and methods for use therewith

Anti-pop circuits are provided for an audio amplifier that uses a power supply voltage and a ground voltage to drive a load with an audio signal that is centered about a virtual analog ground. These anti-pop circuits include a variable resistor and a capacitor that are connected to the audio amplifier to provide a low pass filter. The variable resistor has resistance that varies in response to a voltage level of the virtual analog ground, such as a difference between a voltage level of the power supply voltage and the voltage level of the virtual analog ground. The variable resistor may be a field effect transistor having a gate that is responsive to the differences between the voltage level of the power supply voltage and the voltage level of the virtual analog ground. The capacitor may be a field effect transistor, as well. Related methods are also described.

Anti-pop circuits and methods for audio amplifiers using variable resistors

An audio system includes a CODEC audio jack having left and right audio ports and a jack sense circuit. The jack sense circuit includes left and right amplifiers and a cross-drive impedance sensing circuit. This cross-drive impedance sensing circuit, which is electrically coupled to the left and right audio ports and the left and right amplifiers, detects the resistances of left and right output loads in order to determine characteristics of a device connected to the CODEC audio jack. The cross-drive impedance circuit is configured to measure a resistance of a left output load electrically coupled to the left audio port, in response to a 'right' test signal generated by the right amplifier, and is further configured to measure a resistance of a right output load electrically coupled to the right audio port in response to a 'left' test signal generated by the left amplifier.

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Austin, TX, United States of America

Ajaykumar A Kanji