An adjustment circuit for use with a resistive reference ladder that establishes nominal reference steps and a common mode voltage for a plurality of comparators, such as used in a flash converter. An “H” arrangement of current sources injects current at a first node, VH, and sinks at a second node, VL. with VH, and VL. being coupled to ends of the ladder. The voltage difference between these two nodes thus controls the scale applied to the reference ladder, without affecting a common mode voltage reference Vcm. Alternatively, the current source may inject current at VL and sink current at VH to decrease the reference for each comparator.