A Class-D Piezoelectric Speaker Driver Using A Quadrature Feedback Chopping Scheme achieving 29dB Large-Signal THD+N Improvement

This paper presents a Class-D piezoelectric speaker driver that employs a quadrature feedback chopping scheme (QCS). Compared to a conventional single feedback chopping scheme (SCS), the use of QCS can eliminate the timing skew between low-voltage (LV) and high-voltage (HV) choppers, greatly improving large-signal linearity. A prototype...

3.1 A 120.9dB DR, -111.2dB THD+N Digital-Input Capacitively-Coupled Chopper Class-D Audio Amplifier

Class-D amplifiers (CDAs) are widely used in audio applications where a high power efficiency is required. As most audio sources are digital nowadays, implementing digital-input CDAs results in higher levels of integration and lower cost. However, prior open-loop digital-input CDAs suffer from high jitter sensitivity and output-stage...

A Chopper Class-D Amplifier for PSRR Improvement Over the Entire Audio Band

The power supply rejection ratio (PSRR) of conventional differential closed-loop Class-D amplifiers is limited by the feedback and input resistor mismatch and finite common-mode rejection ratio (CMRR) of the operational transconductance amplifier (OTA) in the first integrator. This article presents a 14.4-V Class-D amplifier employing...

A 121.4dB DR, -109.8dB THD+N Capacitively-Coupled Chopper Class-D Audio Amplifier

Class-D amplifiers (CDAs) are often used in audio applications due to their superior power efficiency. Due to the sensitivity of the human ear, a large dynamic range (DR) is desired, and audio DACs with up to 130dB DR are commercially available [1]. However, the DR of the CDAs they drive is typically much lower [2]-[4], mainly due to the...

A -91 dB THD+N Resistor-Less Class-D Piezoelectric Speaker Driver Using a Dual Voltage/ Current Feedback for LC Resonance Damping

Piezoelectric speakers are gaining popularity on account of their improving form-factor and audio quality, making them a good fit for many audio applications such as in televisions, laptops, etc. Such speakers can be modelled as a large capacitive load, and so are typically driven by a Class-AB amplifier via a series resistor that ensures driver...

A 121.4-dB DR Capacitively Coupled Chopper Class-D Audio Amplifier

This article presents a class-D amplifier (CDA) with high dynamic range (DR). To eliminate the typically dominant noise contribution of a resistive feedback network, the input and feedback signals are chopped and applied to a capacitive feedback network. However, this leads to high-voltage (HV) transients at the input of the loop filter,...

A − 91 dB THD + N, Class-D Piezoelectric Speaker Driver Using Dual Voltage/Current Feedback for Resistor-Less LC Resonance Damping

This article presents a Class-D audio amplifier for capacitive piezoelectric speaker loads. Employing a dual voltage feedback (VFB)/current feedback (CFB) topology, the amplifier is capable of damping LC resonance without using an external damping resistor, therefore reducing system power consumption, cost, and size. Additional power savings are...

A - 121.5-dB THD Class-D Audio Amplifier With 49-dB LC Filter Nonlinearity Suppression

Class-D audio amplifiers produce electromagnetic interference (EMI), which often needs to be suppressed by an external LC filter. However, due to component nonlinearity, this filter can itself cause significant distortion. This article presents a class-D amplifier that suppresses LC filter nonlinearity by 49 dB and is robust to ±30%...

A -109.1 dB/-98 dB THD/THD+N Chopper Class-D Amplifier with >83.7 dB PSRR Over the Entire Audio Band

This paper reports a chopper Class-D audio amplifier that obtains high PSRR over the entire audio band. A chopping scheme is proposed to minimize intermodulation distortion between pulse-width modulation (PWM) and chopping in the audio band. A high-voltage chopper is developed to handle a 14.4 V PWM signal. Timing matching techniques are...

A High-Linearity and Low-EMI Multilevel Class-D Amplifier

This article presents a Class-D audio amplifier for automotive applications. Low electromagnetic interference (EMI) and, hence, smaller LC filter size are obtained by employing a fully differential multilevel output stage switching at 4.2 MHz. A modulation scheme with minimal switching activity at zero input reduces idle power, which is...