Mean quantisation noise power for an SPT analogue-to-digital converter

The mean quantisation noise power introduced by a signed power-of-two (SPT) analogue-to-digital converter (ADC) is determined. This type of converter approximates an integer (in two´s complement format), obtained from an ADC with uniformly distributed quantisation levels, using a signed power-of-two number. The mean quantisation noise power is shown to be strongly dependent on the number of terms used in the signed power-of-two approximation while being largely independent of the two´s complement number wordlength