Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
Usually class AB crossover distortion is low. Never hear crossover gain is low. The distortion is low, because both high side and low side is turn on at the cross over range
Really? but the crossover distortion of class B>class AB>class A, and we will try to decrease class AB's crossover distortion, deesn't it?
kwkam said:
Usually class AB crossover distortion is low. Never hear crossover gain is low. The distortion is low, because both high side and low side is turn on at the cross over range
A power amplifier's push-pull output stage is made with a pair of complementary emitter-follower transistors that have a voltage gain of 1.
Class-B has plenty of horrible crossover distortion.
Class-AB is biased for a little idle current and has no crossover distortion.
A class-A power amplifier is a room heater.
I think classab also has crossover distortion, the more bias current, the less distortion.
Audioguru said:
A power amplifier's push-pull output stage is made with a pair of complementary emitter-follower transistors that have a voltage gain of 1.
Class-B has plenty of horrible crossover distortion.
Class-AB is biased for a little idle current and has no crossover distortion.
A class-A power amplifier is a room heater.
No.
When the idle current in the output transistors is correct at about 20mA to 60mA, the crossover distortion is gone. When the current is higher then a different type of crossover distortion is produced.
You cannot see crossover distortion on an oscilloscope nor hear it from class-AB audio power amplifiers and audio opamps.
Some extremists take an OPA2134 audio opamp that has distortion of only 0.00008% from their class-AB output stage and add a load resistor to operate its output in class-A to "reduce?" the distortion.
Ok.
But if the quiescent current increase to 20mA, the classab may has the classA's characteristic, so the crossover distortion is gone; if decrease the current, the classab will resemble classB, and have large crossover distortion, isn't it?
Audioguru said:
incol said:
I think classab also has crossover distortion, the more bias current, the less distortion.
No.
When the idle current in the output transistors is correct at about 20mA to 60mA, the crossover distortion is gone. When the current is higher then a different type of crossover distortion is produced.
You cannot see crossover distortion on an oscilloscope nor hear it from class-AB audio power amplifiers and audio opamps.
Some extremists take an OPA2134 audio opamp that has distortion of only 0.00008% from their class-AB output stage and add a load resistor to operate its output in class-A to "reduce?" the distortion.
Make a complementary emitter-followers output stage wuth adjustable bias current. Feed in a very low distortion signal and measure the distortion on a distortion analyser while you adjust the bias current.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
