# Change current of bandgap

Here is my bandgap,and i want to change the current "I" ,according to the formula:

I=$\frac{nk\times lnK}{qR}$, n,k and q are constant

So i can only change $lnK$ and R to adjustment the current,the calculation of $ln$ is too complicated ,so i choose to change the value of R,after i change it,the voltage before R1 change,but the current does not ,what do i miss for adjusting the current?

• Pro tip: instead of drawing 8 PNPs in parallel there's an option "mult" which you can set to 8 and then one symbol gives you 8 transistors in parallel. – Bimpelrekkie Nov 11 '17 at 12:13
• actually i know that,thx @Bimpelrekkie – Shine Sun Nov 11 '17 at 12:21
• The resistor value should influence the current as it changes the current where the current through Q1 and R2 are equal. I suspect something else is going on. If you annotate the DC operating points and node voltages maybe things will become more clear. – Bimpelrekkie Nov 11 '17 at 12:27
• @Bimpelrekkie like this? – Shine Sun Nov 11 '17 at 13:17
• Uh, I only see the operating point info of the resistors. No node voltages which are the first thing I'd want to see. – Bimpelrekkie Nov 11 '17 at 21:43