Audio Designers and PSRR

Designers of consumer radio electronics are increasingly going for closed and open loop Class D amplifiers. But if you want to capture the amplifier performance adequately, you need to look at the power supply ripple effects in a different way.

Audio designers today are confronted with a slew of problems like reducing the size of the form factors, reducing the cost of the system and creating high quality audio.

The problem is, if you want to achieve any of these objectives, your supply noise reduction architecture should be of a high order. Unfortunately, current power supply rejection measurements are unable to properly capture Class D amplifier performance. Custom power supplies can make a world of difference here.


Historically, power supply rejection was a good indicator of how an amplifier’s output measured in terms of supply noise rejection. On the other hand, the increasing availability of Class D amplifiers and their advantages means, we can no longer exclusively rely on the power supply rejection ratio to indicate supply noise rejection.

The development of Class D amplifiers actually changed the dynamics of the market. It led to important innovations in industrial design like smaller form factors. At the same time, Class D amplifiers had a fundamentally different configuration than Class AB amplifiers.

So embedded engineers must be prepared. In all probability, Class AB amplifiers will become en passe and will be replaced by Class D amplifiers.