In Reply to: RE: Neutralization of Miller capacitance posted by Tre' on March 11, 2017 at 16:00:06:
searching the forum. I guess what you meant was the post by Lynn Olson (linked below).
Lynn's objection was that neutralization would only work under condition of perfect balance. Any imbalance (e.g. transition into Class B) will cause positive feedback exceeding negative feedback and causing bursts of oscillation.
This is a real problem indeed, but there are at least two ways to mitigate it. First, a differential stage can be forced into complete symmetry (pure Class A) by a CCS or a choke. Second, neutralizing capacitors can be made smaller than Cpg, which will cause partial rather than complete neutralization, but safeguard against excessive positive feedback.
Yet another source of problems could be imperfections in neutralizing capacitors introducing distortion at the critical signal juncture. However, since capacitances in question are relatively low, very high quality capacitors can be used. Vacuum caps come to mind.
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Topic - Neutralization of Miller capacitance - sser2 15:29:24 03/11/17 (24)
- Why not just use a 6SN7? - Ralph 12:11:36 03/13/17 (10)
- 6SN7 - sser2 14:15:47 03/13/17 (9)
- 6SL7 - drlowmu 00:20:05 03/20/17 (8)
- RE: 6SL7 - GeorgePope 01:36:42 03/20/17 (7)
- Four legs good, eight legs bad??? - cpotl 17:54:16 03/20/17 (2)
- RE: Four legs good, eight legs bad??? - used-hifi 18:00:54 03/20/17 (1)
- RE: Four legs good, eight legs bad??? - PakProtector 04:33:05 03/22/17 (0)
- RE: 6SL7 - drlowmu 08:53:34 03/20/17 (3)
- RE: Neutralization of Miller capacitance - Lew 10:29:28 03/12/17 (5)
- RE: Neutralization of Miller capacitance - sser2 13:40:42 03/12/17 (4)
- RE: Neutralization of Miller capacitance - megasat16 16:06:26 03/11/17 (0)
- RE: Neutralization of Miller capacitance - Tre' 16:00:06 03/11/17 (5)