Headphone Amplifier Research Articles

An 82-mW ΔΣ-Based Filter-Less Class-D Headphone Amplifier With −93-dB THD+N, 113-dB SNR, and 93% Efficiency

A low-power 113-dB SNR, −93-dB total harmonic distortion (THD)+N, digital input <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> -based filter-less Class-D amplifier for wireless headphone applications is presented. This performance is achieved by the following architecture improvements: 1) variable-frequency- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> Class-D with digital feed-forward and switching-frequency reduction, 2) common-mode-stabilized power stage, 3) current digital-to-analog converter direct drive, and 4) rotational first-order dynamic-element-matching techniques. It operates on a single 1.8-V power supply with no external passive components except for a supply decoupling capacitor. The Class-D headphone amplifier achieves 82-mW non-clipping output power with 93% efficiency at a 16- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> and 33- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{H}$ </tex-math></inline-formula> load condition. The complete system was fabricated in a 40-nm CMOS process and occupies 1.33-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> die area.

Research and Design of Integrated System of Headphone Amplifier Based on Bluetooth Technology

Traditional earphones and speakers need to use audio cables to connect mobile devices and sounding units when using audio files of mobile devices such as mobile phones as audio input sources. This paper proposes a solution to this problem. This paper studies and designs a power headphone amplifier integrated system based on Bluetooth technology with STM32F407 as the main control core. The system uses CSR8670 Bluetooth audio SoC chip to realize Bluetooth audio transmission, uses TPA6112 headphone audio amplifier to realize amp function, uses HT8696 class D power amplifier to realize speaker power amplifier function, uses 3.2 inch resistive touch screen to realize human-computer interaction function, and the system introduces STemWin graphics library Implement human-machine UI interface. The system is more practical in the independent output of the amp and the speaker power amplifier circuit, the control method is more humanized, and the human-machine experience is better, which plays a driving role for the popularization of the smart home.

A Performance-Aware Low-Quiescent Headphone Amplifier in 65-nm CMOS

A low-quiescent high-performance class-AB headphone amplifier is presented. The effect of the input-referred offset on the quiescent power of audio power amplifier (APA) that drives very small resistive load is described and analyzed. A digitally assisted offset calibration-based APA topology together with improved frequency compensation is proposed. This permits the use of low quiescent power and small compensation capacitance. Implemented in 65-nm CMOS technology, the amplifier occupies an area of 0.15 mm2 and consumes 0.4 mW at ±1 V supplies. At the load of 16 $\Omega $ //200 pF, the gain-bandwidth product is 1.78 MHz using a total compensation capacitance of 8.5 pF. Other performance metrics are measured with −89-dB total harmonic distortion (THD+N), 93.5-dB signal-to-noise ratio, 84-dB power supply rejection ratio (PSRR+), and 105-dB PSRR– @217 Hz. It can deliver a peak power of 35 mW (1.5 $V_{\mathrm{ pp}}$ swing) to the above load, yielding the best figure-of-merit (FOM) = (peak load power/quiescent power) and the best FOM2 = [peak load power/quiescent power $\ast $ (THD+N)%] with respect to other reported representative works.

A Load-Adaptive Class-G Headphone Amplifier With Supply-Rejection Bandwidth Enhancement Technique

This paper presents a load-adaptive Class-G headphone amplifier to improve the power efficiency for different headphone impedances. For an impedance value, the amplifier utilizes two techniques, voltage rails selection and Class-G switching activity control, to reduce the power dissipation of the amplifier and the power loss of a Class-G power generator, respectively. In addition, a supply-rejection bandwidth enhancement technique for the Class-AB output stage is proposed to suppress the out-of-band noise by the Class-G supply rails switching. Compared with the conventional fixed 2-level Class-G amplifier, the integrated $0.18~\mu \text {m}$ CMOS amplifier improves the total-path efficiency to 37% from 31% (1.45 mA current can be saved from a 1.8 V supply) while delivering 5 mW into a $16~\Omega $ . The PSRR of the amplifier is 130 dB at 217 Hz and is still larger than 100 dB up to 20 kHz. Finally, the decoder and amplifier together achieve 108 dB DR and 95 dB SNDR with a $16~\Omega $ headphone load.

Review: dragonfly DACS upgrade your smartphone's audio with these slim digital-to-analog converters [Resources

If you're a music lover, you probably know that plug-in devices are available to improve the audio quality of music files played back from your smartphone or laptop. The most intriguing of these devices combine a digital-to-analog converter (DAC) with a headphone amplifier. These USB DAC-headphone amps have been around for a few years, but some are as big as a phone themselves.

Electroacoustical evaluation of a prototype headphone amplifier for educational purposes

In several classroom activities, it is required to feed a signal simultaneously to several headsets to have students listening to the same sound signal, e.g., to show binaural effects. To drive several headphones, an appropriate headphone amplifier is needed. The aim of this work was to build a prototype of a simple headphone amplifier based on a publicly available project around different types of operational amplifiers and test its electrical and acoustical performance when used with typical headphones. Frequency response function, total harmonic distortion, and signal-to-noise ratio were evaluated. Among the different OPAMPs the OPA2134 showed the best performance, especially because of the very flat frequency response function in the hearing range, low harmonic distortion, and superior SNR (−83 dBFS). Acoustical test were therefore performed based on the amplifier with the OPA2134 only, using a Sennheiser HD 600 headphone and a Sennheiser KR4 microphone. THD measured with this configuration ranged from −86 [email protected] kHz and global SPL = 70 dB to −35 [email protected] Hz and global SPL = 110 dB. At all, the test showed that the amplifier circuit is appropriate for the required application, taking into account that it is very simple and can be mounted easily by the students.

Perceived Simultaneity with Crossmodal Pairs of Stimuli

Human observers acquire information about physical properties of the environment through different sensory modalities. Temporal coincidence of sensory information has been identified as an important cue to aid the organization of signals into a coherent representation of events. Perceived simultaneity, successiveness, and temporal order are thus important properties when dealing with multiple signals. Perceiving the correct timing of stimuli might seem a trivial problem, however stimuli in different sense modalities generated in synchrony by the same distal event could be perceived as being successive because of different physical transmission speed and processing latency. To complicate things even further there are stimulus dependent delays, stimulus interferences, compensations for differential delays, effects of adaptation, and biases due to the task that complicate the relation between physical timing of stimuli and the simultaneity measured in psychophysical experiments.This tutorial comprises a lecture that outlines several basic methods to characterize perceive simultaneity of crossmodal stimuli. We will describe the necessary steps to set up an experiment. Some of the common pitfall and shortcoming of different experimental designs will be discussed. Data analysis for simultaneity and temporal order judgments will be sketched, as well as possible conclusions that could be achieved from their comparison.The second part of the tutorial will be a practical demonstration where students will set up an experiment to measure perceived simultaneity between stimuli in the auditory, visual, and tactile modality. Interested participants should bring their own laptop with a working copy of Matlab. The laptop needs to have a 3.5mm stereo headphone plug. All three kinds of stimuli will be generated in pairs using the audio card, an additional headphone amplifier (provided), and LEDs, speakers, and tactors. Matlab code will be provided to generate stimuli, collect the responses and analyze the data.Suggested reading:Vroomen & Keetels (2010). Perception of intersensory synchrony: A tutorial review. Attention, Perception, & Psychophysics, 72(4), 871-884. doi:10.3758/APP.72.4.871. Can be downloaded here: http://spitswww.uvt.nl/∼vroomen/Pubs/70.pdf

Design of a Signal Conditioning Device for Remote Breath and Swallowing Sounds Recording

Design of a Signal Conditioning Device for Remote Breath and Swallowing Sounds Recording

A Class-G Headphone Amplifier in 65 nm CMOS Technology

This paper presents a class G amplifier based on a low distortion switching principle technique called switching currents injection. The switching circuit enables a very smooth handover between the voltage supply rails obtaining both high efficiency and low distortion. An approach for the evaluation of the switching distortion in a class G amplifier (and the ability of the loop to reject it) is proposed and the results obtained are used to optimize the overall distortion after compression by the feedback loop. The integrated 65 nm CMOS class G headphone driver based on the above concept operates from ±1.4 V and ±0.35 V supplies. At low power level it uses almost exclusively the low voltage supply reducing the dissipation to 1.63 mW @ Pout = 0.5 mW into 32 Ω. At higher power level, where both supplies are used, the smooth transition between the rails allows a THD + N better than -80 dB for Pout ≤ 16 mW into 32 Ω. The SNR is 101 dB, quiescent power is 0.41 m W and active die area is 0.14 mm2.

Method and system for automatically detecting and powering PC speakers

A method of powering an audio output device of a computer system, by determining whether a passive or active audio output device is connected to an audio output jack of the computer system and, based on this determination, providing an appropriate power level to the audio output jack. For example, if the determination is made that a passive audio output device is connected to the audio output jack, then a 3-watt power signal is applied to the audio output jack, but if the determination is made that an active audio output device is connected to the audio output jack, then a ¼-watt power signal is applied to the audio output jack. The type of audio output device present may be determined by sensing an impedance at the audio output jack. This sensing may be performed by comparing a load voltage associated with the impedance to a reference voltage. The output of a switch device (multiplexer) having a first input from an AC97 audio codec and headphone amplifier and a second input from a passive speaker amplifier is selectively controlled by the sensing circuit.

Integrated direct drive inductor means enabled headphone amplifier

A headphone driver amplifier operative from a single DC voltage supply, coupled directly to the headphone speakers without the need for DC coupling capacitors used for preventing DC reaching the headphones. An onboard power supply generates a negative voltage rail which powers the output amplifiers, allowing driver amplifier operation from both positive and negative rails. Since the amplifiers can be biased at ground potential (O volts), no significant DC voltage exists across the speaker load and the need for DC coupling capacitors is eliminated.