I'm designing a bandgap reference and my initial schematic test consists of two sets of 8 PNPs in parallel through which I'm passing DC currents at a ratio of 10:1 (20uA : 2uA), and therefore a current density ratio of 10:1. From the equation I'm expecting to get a delta Vbe of ln(10)*kT/q=59.5mV at 300K but I'm actually getting 64mV. To get ~59.5mV I have to set the temp to 279K. Can anyone explain this to me? @User I think I saw you did a bandgap ref. right? See schematic below: