Output stages using only n-type enhacement transistors

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
Hi everyone,

I've been trying for the last couple of months to produce an amplifier using only IGZO transistors.
Due to production constraints, I wondered if, since 1998, there haven't been any developments on paralleling transistors for the output stage.
Is it my only option? A 1% efficiency circuit??
I'm using this book as my reference
https://www.sciencedirect.com/book/9780750626293/high-performance-audio-power-amplifiers
I appreciate any help you can provide.
 

BobTPH

Joined Jun 5, 2013
4,322
What does paralleling output transistors have to do with efficiency?

The only way you are getting close to 1% efficiency is with a class D amplifier.

Bob
 

dl324

Joined Mar 30, 2015
13,857
I wondered if, since 1998, there haven't been any developments on paralleling transistors for the output stage.
That has been done for decades. If you're doing this with discrete devices, you have to deal with more issues. For integrated circuits, it's easier to get matching so putting devices in parallel is commonly done; even for non-power applications.
 

LowQCab

Joined Nov 6, 2012
1,635
The question is ..........
Why are You trying to reinvent the Wheel ?
It's going to either be PWM, or Linear.
Crazy amounts of power is best handled by multiple Amplifiers and higher Speaker-Impedances.
( And, of course, mounting the Amps to the Speakers ).

What do You see as the advantage of the IGZO-Transistors in an Audio-Amp ?
.
.
.
 

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
I'm trying to finish my master's degree after realizing that I'm trying to bite more than I can chew.
The thing is, It's already been done, and it's only reported in one article, and by using a-IGZO transistors, we can try to embed the audio amplifier in a flexible screen with a flexible speaker as well. I've never designed an amplifier, and I'm still trying to figure out the essential information to show
The question is ..........
Why are You trying to reinvent the Wheel ?
It's going to either be PWM, or Linear.
Crazy amounts of power is best handled by multiple Amplifiers and higher Speaker-Impedances.
( And, of course, mounting the Amps to the Speakers ).

What do You see as the advantage of the IGZO-Transistors in an Audio-Amp ?
.
.
.
.
 

Papabravo

Joined Feb 24, 2006
17,646
I'm trying to finish my master's degree after realizing that I'm trying to bite more than I can chew.
The thing is, It's already been done, and it's only reported in one article, and by using a-IGZO transistors, we can try to embed the audio amplifier in a flexible screen with a flexible speaker as well. I've never designed an amplifier, and I'm still trying to figure out the essential information to show


.
It's not looking good for you if the semester is over in two weeks. Consider punting and have another go next semester.
 

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
Hi Everyone,

I've been currently trying to implement an analog amplifier using a-IGZOs and would like to hear
some commentaries about the proposed circuit that I'll try to discuss in my presentation master thesis.
1638904076458.png
Any questions are welcomed!!
 

dl324

Joined Mar 30, 2015
13,857
Since this is still school work, it should be in the Homework Help forum so we don't do your work for you.
 

Ian0

Joined Aug 7, 2020
4,169
Hi Everyone,

I've been currently trying to implement an analog amplifier using a-IGZOs and would like to hear
some commentaries about the proposed circuit that I'll try to discuss in my presentation master thesis.
View attachment 254481
Any questions are welcomed!!
How about connecting the Gate of T22 to the Gate of T25?
Are you able to make depletion mode transistors, or is enhancement the only option?
 

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
How about connecting the Gate of T22 to the Gate of T25?
Are you able to make depletion mode transistors, or is enhancement the only option?
It could be done but I don't see the point in doing it. The current driver can be later substituted by a class A or a class amplifier. This is just the pre-amp.
I'm limiting it to only enhancement due to production limitations and no models for depletion ones.
 
Last edited:

Ian0

Joined Aug 7, 2020
4,169
I'm limiting it to only enhancement due to production limitations and no models for depletion ones.
OK. If you could do depletion, I'd recommend the SRPP circuit, but if not, try connecting the Gate of T22 to the Gate of T25, so that T25 is on when T26 is off and vice versa.
 

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
And regarding information. What do you think is the necessary information that needs to be presented for you to completely understand this circuit? I'm currently presenting the voltage gain, aspect ratios, voltage supply, and feedback loop resistors as well as the bandwidth. Is there anything I'm missing ??
 

dl324

Joined Mar 30, 2015
13,857
I did it, there is a separation between gate and channel. The line is probably just a bit to bold. Thanks :)
Then you drew the devices as depletion mode. When I hand draw, I don't bother with the solid/dashed line bit, but on a schematic that gets published, I'm going to draw the symbol correctly.
 

Thread Starter

dumbinvestor

Joined Feb 17, 2020
25
Then you drew the devices as depletion mode. When I hand draw, I don't bother with the solid/dashed line bit, but on a schematic that gets published, I'm going to draw the symbol correctly.
I don't expect the thesis to be published but thanks for the recommendation :)
 
Top