An apparatus, such as a coherent optical receiver, includes a transimpedance amplifier (TIA) with differential outputs, and a multi-tanh type current limiter connected across the differential outputs of the transimpedance amplifier. The multi-tanh type current limiter includes two tanh-type current limiters shifted in voltage and connected to subtract an output current thereof from an output current of the TIA.

A microprocessor-based ALC (automatic level control) system, for original manufacture or field maintenance and retrofit, providing the stability, reliability and longevity of digital solid state implementation along with ALC characteristics calibrated to one or more programed sets of ALC performance specifications. The ALC system can be embodied as a professional audio ALC amplifier with a purely analog main signal path including an ECA (Electronically Controlled Attenuator) controlled by a highly stable microprocessor-based signal level transducer, an ALC calibrator that can be incorporated into any system, ALC system or ALC-related module thereof, or deployed as stand-alone test equipment, to provide ALC performance and/or automatic recalibration of existing ALC circuitry, compensating components thereof to meet programed ALC performance specifications and thus remedy problems and shortcomings relating to stability, reliability, longevity and/or ALC performance.

A microprocessor-based ALC (automatic level control) system, for original manufacture or field maintenance and retrofit, providing the stability, reliability and longevity of digital solid state implementation along with ALC characteristics calibrated to one or more programed sets of ALC performance specifications. The ALC system can be embodied as a professional audio ALC amplifier with a purely analog main signal path including an ECA (Electronically Controlled Attenuator) controlled by a highly stable microprocessor-based signal level transducer, an ALC calibrator that can be incorporated into any system, ALC system or ALC-related module thereof, or deployed as stand-alone test equipment, to provide ALC performance and/or automatic recalibration of existing ALC circuitry, compensating components thereof to meet programed ALC performance specifications and thus remedy problems and shortcomings relating to stability, reliability, longevity and/or ALC performance.

A circuit assembly for correction of an input signal including a useful signal and a disturbance signal comprises: a voltage-controlled circuit having at least one voltage-controlled circuit element, an input interface and an output interface, a resistor connected upstream of the voltage-controlled circuit in series with the voltage-controlled circuit, an operational amplifier having a first amplifier input, a second amplifier input and an amplifier output, and a low-pass filter connected between the input interface of the at least one voltage-controlled circuit element and the first amplifier input of the operational amplifier, wherein the output voltage from the operational amplifier is fed back to the low-resistance terminal of the circuit element in that the low-resistance terminal of the at least one voltage-controlled circuit element is electrically connected to the amplifier output of the operational amplifier and to the second amplifier input of the operational amplifier.

When, in conventional sound systems, signals of sounds collected by a microphone are amplified and the amplified signals are applied to an ear by an earphone and a headphone, too loud sounds and environmental noises are unpleasant, and the intelligibility of words are poor. Hence, such problems are to be addressed. In addition, downsizing and performance improvement for sound apparatuses are to be accomplished. A signal having undergone an amplitude limitation with reference to an output potential of a high cut filter 17 which is an output by a low cut filter 12 in a high frequency band and inverted by an inverter 14 is added with, by an adder 15, an output signal from the high cut filter 17, and an addition signal is output.

When, in conventional sound systems, signals of sounds collected by a microphone are amplified and the amplified signals are applied to an ear by an earphone and a headphone, too loud sounds and environmental noises are unpleasant, and the intelligibility of words are poor. Hence, such problems are to be addressed. In addition, downsizing and performance improvement for sound apparatuses are to be accomplished. A signal having undergone an amplitude limitation with reference to an output potential of a high cut filter 17 which is an output by a low cut filter 12 in a high frequency band and inverted by an inverter 14 is added with, by an adder 15, an output signal from the high cut filter 17, and an addition signal is output.

A headset having game, chat and microphone audio signals is provided with a programmable signal processor for individually modifying the audio signals and a memory configured to store a plurality of user-selectable signal-processing parameter settings that determine the manner in which the audio signals will be altered by the signal processor. The parameter settings collectively form a preset, and one or more user-operable controls can select and activate a preset from the plurality of presets stored in memory. The parameters stored in the selected preset can be loaded into the signal processor such that the sound characteristics of the audio paths are modified in accordance with the parameter settings in the selected preset.

A headset having game, chat and microphone audio signals is provided with a programmable signal processor for individually modifying the audio signals and a memory configured to store a plurality of user-selectable signal-processing parameter settings that determine the manner in which the audio signals will be altered by the signal processor. The parameter settings collectively form a preset, and one or more user-operable controls can select and activate a preset from the plurality of presets stored in memory. The parameters stored in the selected preset can be loaded into the signal processor such that the sound characteristics of the audio paths are modified in accordance with the parameter settings in the selected preset.

The present invention discloses a speaker device and electronic equipment. The speaker device comprises a speaker body, an audio signal input terminal connected with the speaker body, and a DC voltage signal input terminal connected with the speaker body. The electronic equipment comprises the speaker device and a DC voltage signal output circuit. The present invention further discloses a method for reducing a low frequency distortion degree of the speaker of the electronic equipment, and the method is realized by additionally providing a DC voltage signal to the input end of the speaker. In the present invention, a distortion degree of the speaker device at a low-frequency working condition can be reduced, and inconsistency of low frequency distortion of the speaker device, caused by mass production, can be reduced.

The present invention discloses a speaker device and electronic equipment. The speaker device comprises a speaker body, an audio signal input terminal connected with the speaker body, and a DC voltage signal input terminal connected with the speaker body. The electronic equipment comprises the speaker device and a DC voltage signal output circuit. The present invention further discloses a method for reducing a low frequency distortion degree of the speaker of the electronic equipment, and the method is realized by additionally providing a DC voltage signal to the input end of the speaker. In the present invention, a distortion degree of the speaker device at a low-frequency working condition can be reduced, and inconsistency of low frequency distortion of the speaker device, caused by mass production, can be reduced.