out across resistor r 2 as a result less current is applied to the base of transistor q 6 transistor q 6 however is left with enough current to keep it on yet it does not source any current through the output node out transistor q 5 is more sensitive to changes in the input voltage applied at input node v in than transistor q 1 the emitter voltage of transistor q 5 is applied to the base of transistor q 7 since the input voltage v in increases the base emitter voltage of transistor q 5 with respect to u2212 v cc a positive voltage is applied to the base of transistor q 7 as a result the collector voltage of q 7 is negative u2014 the output stage 10 is thus sinking current due to the increase in current i 3 through transistor q 5 more current is applied to the base of transistor q 7 accordingly transistor q 7 sinks more current transistors q 1 q 2 q 4 q 5 and q 7 form a translinear loop the kirchoff 39 s voltage equation provides that vbe q1 vbe q4 vbe q5 vbe q7 assuming r 1 0 1 v t ln i 1 a q1 i s v t ln i 2 a q4.