Automatic component meter range design using floating-point conversion

The control of dynamic range and resolution in the conversion of the voltage and current signals on whose measurement depends the operation of a modern electronic component meter or 'bridge' is a major problem in design. The paper presents a modified form of dual-slope analogue-to-digital convertor for this purpose. Called adaptive acquisition time (AAT) conversion, the technique directly produces a floating-point binary output representation of the signal for subsequent computation purposes. The AAT convertor leads to a bridge range design procedure resulting in a maximum variation of convertor counts of only 2.1 over the entire resistance range of the instrument from 0.5 - to 8 M-. The design of the excitation circuit resulting from the use of AAT conversion itself leads to an autoranging system faster in operation than conventional step-by-step methods. A technique for reducing the sensitivity of the integrator to timing errors in the acquisition period when unfiltered signals.