Is cklass B amplifier BOTH linear and non-linear

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Seeking the opinions of gurus on this newsgroup. The bare bones class B amplifier has zero base|gate bias. A class F amplifier is an extension of the class B with harmonic tuning. So, is class B linear or non-linear.

Re: Is cklass B amplifier BOTH linear and non-linear
On Tuesday, November 19, 2019 at 3:06:13 PM UTC+11, amal banerjee wrote:
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Class B doesn't involve deliberate switching, so it's linear. Class A/B, where the two output devices carry a low, equal current when the output is zero, gives a rather more nearly linear input to output relationship.

The linear/switching distinction doesn't seem to be depend on the "linear" components giving a perfectly linear input-to-output relationship (which is an unattainable ideal anyway).

This seems to be more a linguistic question than a technical one.

--  
Bill Sloman, Sydney

Re: Is cklass B amplifier BOTH linear and non-linear
On Mon, 18 Nov 2019 20:06:08 -0800 (PST), amal banerjee

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It's a matter of definitions and opinions, so there's no good answer.



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Is cklass B amplifier BOTH linear and non-linear
Verbally challenged  amal banerjee wrote:

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** Grovel,grovel ...  


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** Get your term right, FFS.  

 Class B usually invloves a two device, push-pull stage.

 Single device examples are an abortion used only in the world of RF.  

 The former can be quite linear.  

 The latter not so much.  



.....  Phil




Re: Is cklass B amplifier BOTH linear and non-linear
On 19.11.19 06:06, amal banerjee wrote:
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The correct bias for a Class B amplifier depends on the device used. The  
definition for Class B is 180 degrees conduction angle, a half cycle off  
and another half cycle more or less on.

There is a difference to Class F: The Class F active element functions  
as a switch and the output is not intended to be controlled by the drive  
signal level.

A Class B push-pull amplifier can be made quite linear (maybe
not enough for Phil ...). A single-ended Class B amplifier as
used in RF is quite envelope-linear, but not linear on the carrier.
The carrier waveform is restored in RF work with a resonant
output circuit.

--  

-TV


Re: Is cklass B amplifier BOTH linear and non-linear
On Monday, November 18, 2019 at 8:06:13 PM UTC-8, amal banerjee wrote:
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Push-pull Class B is essentially regarded as linear, crossover distortion and clipping distortion notwithstanding.

Single ended class B for RF is also regarded as linear, because:
1. the output must have a sufficiently high Q tank (filter), or has enough "harmonic shorting" to effectively restore the missing half-cycle,
2. the dB-for-dB relationship, input to output, exists regardless of half-cycle restoration. That is, if the increase input drive is increased by 1 dB, then the output increases by 1 dB. This dB-for-dB relationship is an RF POV definition of "linear."



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