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Re: transient test - Part II

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Steve Eddy

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In Reply to: transient test - Part II posted by mfc on July 30, 2003 at 21:52:14:

Thanks, mfc!
Have you experimented with different values of the base-emitter resistor on the output device in the Sziklai pair? It's value will effect linearity so you might want to tweak it a bit across a reasonable range and note how the harmonic pattern changes.
se

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Re: transient test - Part II - mfc 11:01:55 07/31/03 (3)

Re: transient test - Part II

Hi,
The top, bottom resistor or both?
I'm using 50 ohms on the top and 10 on the bottom
currently.

Re: transient test - Part II - Steve Eddy 11:07:29 07/31/03 (2)

Re: transient test - Part II

The top, bottom resistor or both?
I'm using 50 ohms on the top and 10 on the bottom
currently.
Top. Say from 20 to oh, 220.
You're using a split +/- 12 volt supply, right?
se

Re: transient test - Part II - mfc 02:04:54 08/01/03 (0)

Re: transient test - Part II

Here are the results for varying the top resistor. I also readjusted
the compensation cap for flat frequency response.

Harmonic Reference Out 1VPeak
Sine 20ohm/2520pF 50ohm/3900pF 200ohm/5970pF

Fundamental
(dB) 0.00 0.00 0.00 0.00

2nd -85.87 -87.57 -84.14 -73.91

3rd -107.71 -99.10 -98.28 -88.49

4th -125.36 -112.43 -111.30 -100.15

5th -141.73 -123.90 -122.93 -110.03

6th -159.34 -134.59 -133.59 -118.95

7th -175.32 -146.46 -143.74 -127.34

8th -176.36 -150.59 -150.78 -135.90

9th -184.79 -156.26 -162.88 -145.65

10th -172.97 -157.02 -159.97 -151.94

11th -182.61 -160.13 -162.08 -158.60

12th -175.80 -158.04 -165.87 -149.91

13th -183.14 -175.17 -156.66 -141.16

The 20 is only slightly better than the 50 ohm. 200 isn't as good.

Re: transient test - Part II - mfc 11:50:53 07/31/03 (0)
Its a split +- 20v supply (simulated).
I'll try some different values for the top.

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Harmonic	Reference Out 1VPeak Sine	20ohm/2520pF	50ohm/3900pF	200ohm/5970pF
Fundamental (dB)	0.00	0.00	0.00	0.00
2nd	-85.87	-87.57	-84.14	-73.91
3rd	-107.71	-99.10	-98.28	-88.49
4th	-125.36	-112.43	-111.30	-100.15
5th	-141.73	-123.90	-122.93	-110.03
6th	-159.34	-134.59	-133.59	-118.95
7th	-175.32	-146.46	-143.74	-127.34
8th	-176.36	-150.59	-150.78	-135.90
9th	-184.79	-156.26	-162.88	-145.65
10th	-172.97	-157.02	-159.97	-151.94
11th	-182.61	-160.13	-162.08	-158.60
12th	-175.80	-158.04	-165.87	-149.91
13th	-183.14	-175.17	-156.66	-141.16