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Car Audio Amplifier Power IC Class AB vs Class D

Power IC is sophisticated application in Audio Amplifier product. There are 2 major solution on the Class AB and Class D. Let’s see the 2 solution’s comparison.

To integrate the Bipolar、CMOS and DMOS process in one chip, Power IC can achieve low cost & high voltage application

  • Bipolar junction transistors offer high speed, high gain, and low output resistance, which are excellent properties for high-frequency analog amplifiers
  • CMOS technology offers high input resistance and is excellent for constructing simple, low-power logic gates.
  • DMOS double-diffused metal–oxide–semiconductor high voltage drive
  • Class AB vs Class D

Class AB amplifier uses linear regulating transistors to modulate the output voltage. The loss in these devices is proportional to the product of the voltage cross it and current through it.

PL=Vce * Ic

Class D amplifier employs MOSFETs which either full ON or OFF. Ideally zero power loss can be achieved. In reality application, there will be power loss in switch device caused by 1)finite transition speed;2)ON state resistance;3)gate charge.

Class AB solution (Quad)

VP=14.4V; RL=2Ω @ 1kHz

curve 1) BTL mode


--read out from chart


Efficiency= Pout/(Pdiss+Pout)=15.4%

Class D solution (Quad)

VP=14.4V; RL=2Ω @ 1kHz


--read out from chart



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