Abstract: A speaker feedback system has a linear current feedback derived from a current sensing resistor. A linear motional feedback from the active speaker driver is derived from a sensing coil mechanically coupled with the driver coil of the speaker, the driver coil receiving electrical energy from the power amplifier. A motional signal correction circuit extracts the motional signal from the sensing coil and feeds to input B of the multiplier. A current filter circuit filters out higher-frequency signals from the current feedback signal and then feeds to input A of the multiplier. A multiplier performs the multiplication function of its two inputs and produces an output. Post-multiplier equalization circuitry that control the feedback gain of the nonlinear feedback system such that it can effectively compensate for the effect of flux modulation over the targeted frequency range. A feedback network feeds the output from post multiplier equalization to the power amplifier.

Abstract: A speaker feedback system has a linear current feedback derived from a current sensing resistor. A linear motional feedback from the active speaker driver is derived from a sensing coil mechanically coupled with the driver coil of the speaker, the driver coil receiving electrical energy from the power amplifier. A motional signal correction circuit extracts the motional signal from the sensing coil and feeds to input B of the multiplier. A current filter circuit filters out higher-frequency signals from the current feedback signal and then feeds to input A of the multiplier. A multiplier performs the multiplication function of its two inputs and produces an output. Post-multiplier equalization circuitry that control the feedback gain of the nonlinear feedback system such that it can effectively compensate for the effect of flux modulation over the targeted frequency range. A feedback network feeds the output from post multiplier equalization to the power amplifier.

Abstract: A semiconductor die includes at least one process monitoring circuit for evaluating at least one process parameter of the semiconductor die. The at least one process monitoring circuit can include a first group of process monitoring circuits for monitoring NFET speed and a second group of process monitoring circuits for monitoring PFET speed. The process monitoring circuits can be distributed at the corners of the semiconductor die. The semiconductor die further includes a voltage control circuit configured to store optimum voltage information corresponding to the at least one process parameter. The voltage control circuit is further configured to selectively provide the optimum voltage information to a system power supply. The voltage control circuit includes a calculated optimum voltage register that stores the optimum voltage information corresponding to the at least one process parameter.

Abstract: A bass reproduction speaker apparatus of the present invention includes: A cabinet with two openings; a speaker unit disposed at the first opening; a bass enhancement member disposed at the second opening; an amplifier for driving the speaker unit; a first detector for detecting a vibration of diaphragm of the speaker unit; a second detector for detecting a vibration of the bass enhancing member; a current sensing circuit for measuring the current through the speaker unit; and feedback circuits for feeding back the signals from the detectors and the current sensing circuit output to the amplifier.

Abstract: A sound reproduction system employs at least one amplifier system and at least one speaker. The speaker provides two negative feedback signals: one indicative of the current through the speaker voice coil and a second indicative of the velocity of the speaker diaphragm. The current signal is provided via a first feedback path to an input of the amplifier in the amplifier system. The velocity signal is provided via a second feedback path to an input of the amplifier. The current signal may be derived from the voltage drop across a resistor placed in series with the speaker voice coil. The velocity signal may be derived from a second voice coil coupled to the diaphragm, or may be derived from a piezoelectric sensor coupled thereto.

Abstract: An improved sound reproduction system employs an amplifier system and a speaker. The system offers greatly improved bass response. The speaker provides two negative feedback signals, one indicative of the current through the speaker voice coil and a second indicative of the velocity of the speaker diaphragm. The velocity signal is provided via the first feedback path to an input of the amplifier of the amplifier system. The current signal is provided by the second feedback path through a bandpass filter to the amplifier input. The velocity measurement may be derived from a second voice coil coupled to the diaphragm, or may be derived from a piezoelectric sensor coupled thereto. The current signal may be derived from the voltage drop across a resistor placed in series with the speaker voice coil.