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Is cklass B amplifier BOTH linear and non-linear

Started by amal banerjee November 19, 2019
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.
On Tuesday, November 19, 2019 at 3:06:13 PM UTC+11, amal banerjee wrote:
> 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.
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
On Mon, 18 Nov 2019 20:06:08 -0800 (PST), amal banerjee
<dakupoto@gmail.com> wrote:

>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.
It's a matter of definitions and opinions, so there's no good answer. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Verbally challenged  amal banerjee wrote:

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> Seeking the opinions of gurus on this newsgroup.
** Grovel,grovel ...
>The bare bones class B amplifier has zero base|gate bias.
** 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
On 19.11.19 06:06, amal banerjee wrote:
> 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.
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
On Monday, November 18, 2019 at 8:06:13 PM UTC-8, amal banerjee wrote:
> 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.
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."