Circuit topologies are introduced which should prove of use to the circuit designer of analog audio amplifiers. The objective is to produce circuits of' modest complexity that overcome the nonlinearities inherent in single-transistor and long-tail pair circuits. This allows amplifiers with excellent linearity to be designed without resorting to overall negative feedback with high loop gains. To...

This paper discusses a new kind of distortion mechanism found in transistorized audio power amplifiers. It is shown that this distortion arises from the multistage feedback loop found in most high-quality amplifiers, provided that the open-loop transient response of the power amplifier is slower than the transient response of the preamplifier. The results of the analysis are verified by measure...

There are many different designs for audio amplifiers. Class-D, or switching, amplifiers generate their output signal in the form of a high-frequency square wave of variable duty cycle (ratio of on time to off time). The square-wave nature of the output allows a particularly efficient output stage, with minimal losses. The output is ultimately filtered to remove components of the spectrum above...

We describe the geometric and engineering design challenges that were overcome to create a new compact, 10-inch diameter spherical loudspeaker array with integrated class-D amplifiers and a 120 independent channel digital audio interface using Gigabit Ethernet. A special hybrid geometry is used that combines the maximal symmetry of a triangular-faceted icosahedron with the compact planar packin...

Transimpedance or current feedback amplifiers are still relatively new to audio applications, since they are pri­ marily designed for video circuits. While the AD846 (an early high-per­ formance example) was successfully used in TAA,1 transimpedance amps may not be completely familiar de­ vices (The AD846 data sheet contains a detailed discussion of transimped­ ance amplifier theory). Interesti...

Out-of-band noise (OBN) is troublesome in analog circuits that process the output of a noise-shaping audio DAC. It causes slewing in amplifiers and aliasing in sampling circuits like ADCs and class-D amplifiers. Non-linearity in these circuits also causes cross-modulation of the OBN into the audio band. These mechanisms lead to a higher noise level and more distortion in the audio band. OBN als...

A description of the square-sine intermodulation measuring method is given. The practical measuring procedure is described, and measurement results of commercial audio power amplifiers and integrated operational amplifiers are presented, in many cases showing appreciable transient intermodulation in units which have excellent total harmonic distortion and SMPTE intermodulation distortion specif...