xconductance of gain device through closing resistors
there is also issue of output offset , output impedance ( roughly closing resistors value , if going low) etc.
thought , nice playground for next few months
addendum - developing ZM's I/V conversion stage for DAC resulted in having dual servos for input and dual servos for output
simple for no active voltage gain stage
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http://ee.sharif.edu/~elec3/06_advanced_opamps.pdf
Found a good article.
IN order to have sufficient drive capability, It seems I would have to do one of the following
1. parallel input pairs to increase gain
2. another stage for increased gain and drive capability
3. output buffer for better drive capability
Looks like the latter two allow fro dropping of servo if done properly, but could be wrong.
Found a good article.
IN order to have sufficient drive capability, It seems I would have to do one of the following
1. parallel input pairs to increase gain
2. another stage for increased gain and drive capability
3. output buffer for better drive capability
Looks like the latter two allow fro dropping of servo if done properly, but could be wrong.
ZM,
What is your comment on the whole bit about it wanting a capacitive load. The Bartola article doesnt seem to mention it as an issue. We could raise the gain of the FE by loadng it with a CCS, but that would also raise Zo, correct. I also like the idea of a resistive load, but understand the benefits off the CCS.
What is your comment on the whole bit about it wanting a capacitive load. The Bartola article doesnt seem to mention it as an issue. We could raise the gain of the FE by loadng it with a CCS, but that would also raise Zo, correct. I also like the idea of a resistive load, but understand the benefits off the CCS.
being folded cascode , second stage will transpose to output no more than amount of current change in preceding stage itself ;
so - folded cascode is nice as level shifter , but usually needing buffer stage afterwards
cap mention ........ not exactly relevant , in my book , except as compensation one
so - folded cascode is nice as level shifter , but usually needing buffer stage afterwards
cap mention ........ not exactly relevant , in my book , except as compensation one
I believe Nelson may have referred to it as a current conveyor. May have been someone else. The current through the folded is wholly dependent on the I of the Jfet input stage, correct. If this is true, and we heavily degenerate the FE, what does this do to the cascodes level shifting abilty. would we be able to bias a common drain stage with its output?
see Uskok or BT or whatever thingie they drew in BT thread
Uskok preamplifier
try to avoid CM if you really don't need it
you know what I made , but that is deliberately completely different path , without folded cascodes and with all other unnecessary gizmos
Uskok preamplifier
try to avoid CM if you really don't need it
you know what I made , but that is deliberately completely different path , without folded cascodes and with all other unnecessary gizmos
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Current in the folded cascode is set by its Vgs. If you use a high value degeneration resistor you can get virtually any folded cascode current you want by changing its Gate voltage. Oops, got stuck in Papa fet mode, but you get the idea. Change the base current on the cascode and you change its operating current. Limited by the voltage drop across the load resistor carrying both differential leg and cascode currents. Too low R and you don't have much gain in the differential. Too high and you run into dissipation issues. Like life, a balancing act.
You can also degenerate gain with resistors on the source side of the jfets.
You can also degenerate gain with resistors on the source side of the jfets.
This has been my reference up to this point.
Based on A75
http://www.diyaudio.com/forums/pass-labs/32477-a75-question-mr-pass.html#post378053
Based on A75
http://www.diyaudio.com/forums/pass-labs/32477-a75-question-mr-pass.html#post378053
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