I made a current mirror with a common collector stage in real life and in LTSPice, for a discrete diff-amp lab, and it works well and more or less matches what I calulate if I choose Ibase1 or measure something. And that matches LTspice too, for GND to+8 or 10V rails, w/ around 320uA.
But when I sweep Vce3 to near 16V-GND on the breadboard , or in a diff-pair circuit w/ +8/-8V rails, I get 785uA sinking into the Imirror in real life. (I never built output section). I need to chart it more tommorw to see where the Vce of the current mirror really puts the current up so high.
The problem is, LTSpice still only predicts 365uA for a Vce of 16V. So something about my 2N3904 is what even LTspice is missing. If I put in a current soucre of 785uA (in the attached diff-amp), then my calulations match LTspice and the actual transistors pretty spot on w/ n=1.03312480007.....how did I memorize that so easy, but not my passwords.
I used a Wheatstone bridge diff-amp circuit (not below) to try matching the 3 BJTs to within a few mV. I can't wait for my SMD3065X to get here and make some curve tracer projects.
But when I sweep Vce3 to near 16V-GND on the breadboard , or in a diff-pair circuit w/ +8/-8V rails, I get 785uA sinking into the Imirror in real life. (I never built output section). I need to chart it more tommorw to see where the Vce of the current mirror really puts the current up so high.
The problem is, LTSpice still only predicts 365uA for a Vce of 16V. So something about my 2N3904 is what even LTspice is missing. If I put in a current soucre of 785uA (in the attached diff-amp), then my calulations match LTspice and the actual transistors pretty spot on w/ n=1.03312480007.....how did I memorize that so easy, but not my passwords.
I used a Wheatstone bridge diff-amp circuit (not below) to try matching the 3 BJTs to within a few mV. I can't wait for my SMD3065X to get here and make some curve tracer projects.
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