Yet another amp - simple inverted with 10x gain, mosfet output stage - Page 5 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th June 2011, 09:52 AM   #41
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Hi Piersma.

You are right. The frontend will be regulated, at least it will have an RC filter wich is not presented in the simulation.

As you point out.. It is a problem with current feedback.
  Reply With Quote
Old 19th June 2011, 06:49 PM   #42
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Quote:
Originally Posted by Piersma View Post
hi Sonnya,

Nice circuit that will provide nice THD figures.

Did you check the PSRR?
By nature the current feedback configuration results in a poor PSRR.

I would run the front end from a regulated supply.

regards,
Piersma
The PSRR from either rail is 41dB.

I have made an linear regulator for the frontstage. It has 64dB rejection onto it.

So PSRR is now up to >100dB.
  Reply With Quote
Old 20th June 2011, 07:33 AM   #43
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Can you not put RC-filters into supply rails?
__________________
lineup
  Reply With Quote
Old 20th June 2011, 07:41 AM   #44
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
I could do that. The amplifier has a flat PSRR of 41dB from 0 - ~6KHz.

If you make an RC filter, the low region of the frequence spectre does not has a big improvement. I could use an RC filter like the one you have described in you own thread (33R + 1000uF) but a active discrete regulator costs the same and will provide aditional 63dB from 0 - 10KHz. Afterwards it will only get better.

it consists of 7 transistors per rail for 0,5DKK per transistor.

Last edited by sonnya; 20th June 2011 at 07:41 AM. Reason: rephrase
  Reply With Quote
Old 21st June 2011, 08:51 PM   #45
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Default pcb layout.

Okay, i have done the layout.

as you can see i have attached it.

It looks complex but you can actually see that it has building blocks.

The center of the pcb is where you have the amp itself. with powersupply and regulator running down the side of the board.

In front you have the input. I have decided to add a servo from my Mirand A1 design as the amp will drift 100mV over temperatur from 0 - 80 degrees celcius.

The integrator is made with an PHE426 capacitor from evox rifa.

The feedback network is CMF55 from vishay/dale. They are 25ppm 0.1% So they are quite stable.

This amp is fully scalable up and down.

I have for fun changed the output mosfet to ZVN/ZVP3310 + 10R degeneration, added ccomp of 2 x 33pF, Lowered the rails to +/-25V,changed the gain to ~4xgain (1k+330R feedback network).

In this configuration it performs extremely well. We are talking distortion figures of 0.004% at 10Vrms into 1K load at 1KHz. at 1Vrms it is down to 0.0003%
Attached Files
File Type: pdf cfb-1pairexc10.pdf (45.5 KB, 209 views)
  Reply With Quote
Old 21st June 2011, 09:00 PM   #46
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Would be fun making layout.
But when I added transistors to library I answered: Simulation only
So, when I transfer to PCB layout I get no devices.
__________________
lineup
  Reply With Quote
Old 21st June 2011, 09:35 PM   #47
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Sounds like you have to change your library.

I have ordered PCB and Stencil for delivery the 1.july. Mosfet are ordered too.

Will be exciting to build them.
Attached Files
File Type: pdf cfb+1pairecx10 schematic.pdf (43.6 KB, 207 views)
  Reply With Quote
Old 21st June 2011, 11:34 PM   #48
Piersma is offline Piersma  Netherlands
diyAudio Member
 
Piersma's Avatar
 
Join Date: Jan 2003
Location: Netherlands
Default Gate resistors

hi Sonnya,

Great to see you are not only simulating but also building this amplifier like OS always does.
I would defenitely increase the gate resistors, 22E is too low in my opinion.

Good luck!
  Reply With Quote
Old 22nd June 2011, 06:42 AM   #49
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
It is a beautiful schematic and amplifier.
Separate frontend supply just make it even better.
The mirrors keep OLG and GNFB at lower level.
Could be a well sounding amp. And still close to Hifi.
__________________
lineup
  Reply With Quote
Old 5th July 2011, 02:32 PM   #50
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Default Bare PCB pictures

They will be assemblied next week.
Attached Images
File Type: jpg DSC01824-2.JPG (86.7 KB, 400 views)
File Type: jpg DSC01823-2.JPG (114.3 KB, 396 views)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simple stereo gain stage ss007 Analog Line Level 156 23rd August 2013 03:52 PM
Wanted: Zero feedback 2-10x gain line stage...prefer symmetrical Ric Schultz Analog Line Level 14 26th February 2011 07:26 PM
Voltage gain stage for Non-NFB MOSFET current amp gripracer Solid State 50 23rd October 2009 02:37 AM
AMP with inverting output stage mosfet fab Solid State 112 28th January 2007 04:32 AM
Elektor op-amp front-end with mosfet CF output stage Dusk Elektor 1 5th April 2006 04:09 AM


New To Site? Need Help?

All times are GMT. The time now is 09:36 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2