110 for example current drawn by capacitor 160 while in a tracking mode can result in a corresponding voltage drop across v be causing inaccurate adc readings additional current in excess of i source from current source 150 flows through the emitter of transistor 140 when v input changes over time this current from emitter of transistor 140 is used to charge capacitor 160 the current i c through capacitor 160 causes the difference voltage v be to vary depending on variations of the input voltage specific compensation or correction techniques will be discussed in more detail later in this specification transistor 140 can exhibit dynamic nonlinearities in driving capacitor 160 owing to the current dependence of the device base emitter voltage v be as discussed current source 150 can provide a fixed bias current i source but capacitor 160 draws a portion of this current proportional to the rate of voltage change across capacitor 160 away from the emitter of transistor 140 the resulting modulation of the base emitter of transistor 140 can be mathematically characterized by the exponential hence nonlinear relationship i emitter i s ue89e uf74d v be v t eq 1 v t u2245 thermal voltage constant of approximately 26 mv room temperature current through capacitor 160 causes nonlinearities in the final voltage across the capacitor after the sampling switch opens these nonlinearities are not corrected by any closed loop feedback loops feedback loop 122.