The compliance of a current source, that is, the range of output voltage over which the output current remains approximately constant, affects the potentials available to bias and operate the circuitry in which the source is embedded. For example, in Fig. 2 the voltage available to the "Load" is the difference between the supply voltage formula_80 and the collector voltage of Q3. The collector of Q3 is the output node of the mirror and the potential of that collector relative to ground is the output voltage of the mirror, that is, formula_81 and the "load" voltage is formula_82. The "load" voltage range is maximized at the minimum formula_83. Also, when a current mirror source is used as an active load for one stage of a system, the input to the next stage is often directly connected between the source output node and the same power rail as the mirror. This may require that the minimum formula_83 be kept as small as possible to simplify biasing the succeeding stage and to make it possible to turn that stage fully off under transient or overdrive conditions.