Jun 21, 2017 #1 S sys_eng Full Member level 4 Joined Aug 3, 2016 Messages 193 Helped 0 Reputation 2 Reaction score 1 Trophy points 18 Activity points 1,489 1)It looks like it has 2 diode connected transistor but the top one has a resistor R17 inside, what purpose is that? 2)10uA dc current source causes a 1.3V drop, why? Attachments cir1.png 19.1 KB · Views: 123 Last edited: Jun 21, 2017
1)It looks like it has 2 diode connected transistor but the top one has a resistor R17 inside, what purpose is that? 2)10uA dc current source causes a 1.3V drop, why?
Jun 21, 2017 #2 erikl Super Moderator Staff member Joined Sep 9, 2008 Messages 8,108 Helped 2,695 Reputation 5,370 Reaction score 2,305 Trophy points 1,393 Location Germany Activity points 44,123 sys_eng said: 1)It looks like it has 2 diode connected transistor but the top one has a resistor R17 inside, what purpose is that? Click to expand... To achieve a (somewhat) higher Vgs - in comparison to a purely diode connected circuit. sys_eng said: 2)10uA dc current source causes a 1.3V drop, why? Click to expand... Why not? A current source ("infinite" impedance!) takes all the voltage which isn't needed by the circuit which it supplies.
sys_eng said: 1)It looks like it has 2 diode connected transistor but the top one has a resistor R17 inside, what purpose is that? Click to expand... To achieve a (somewhat) higher Vgs - in comparison to a purely diode connected circuit. sys_eng said: 2)10uA dc current source causes a 1.3V drop, why? Click to expand... Why not? A current source ("infinite" impedance!) takes all the voltage which isn't needed by the circuit which it supplies.
Jun 22, 2017 #3 S sys_eng Full Member level 4 Joined Aug 3, 2016 Messages 193 Helped 0 Reputation 2 Reaction score 1 Trophy points 18 Activity points 1,489 erikl said: To achieve a (somewhat) higher Vgs - in comparison to a purely diode connected circuit. Why not? A current source ("infinite" impedance!) takes all the voltage which isn't needed by the circuit which it supplies. Click to expand... 1)what advantage is a higher Vgs?
erikl said: To achieve a (somewhat) higher Vgs - in comparison to a purely diode connected circuit. Why not? A current source ("infinite" impedance!) takes all the voltage which isn't needed by the circuit which it supplies. Click to expand... 1)what advantage is a higher Vgs?
Jun 22, 2017 #4 erikl Super Moderator Staff member Joined Sep 9, 2008 Messages 8,108 Helped 2,695 Reputation 5,370 Reaction score 2,305 Trophy points 1,393 Location Germany Activity points 44,123 sys_eng said: 1)what advantage is a higher Vgs? Click to expand... Vds<Vgs . But in your circuit (constant current supply) it isn't an advantage.
sys_eng said: 1)what advantage is a higher Vgs? Click to expand... Vds<Vgs . But in your circuit (constant current supply) it isn't an advantage.