Digital/analog conversion device, method of implementation and use in near-field microscopes, comprising digital device for control of inputs to two converters and output of processing unit
The conversion device comprises two digital/analog converters (20,22) with outputs to a processing unit (25) which contains means for selecting one of the outputs of the converters and obtaining an identical conversion law for transmission to the multiplex output of the unit, and a digital device (24) for the control of the inputs to the converters (20,22) and the output of the processing unit (25). The processing unit (25) contains two operational amplifiers (26,28) connected at the outputs of the converters (20,22), where the gain and the offset of operational amplifiers are controlled by a fine adjustment of potentiometers (27, 29), and the outputs of operational amplifiers are connected to a fast switching device (30). When a new digital value E(n) is applied to the second converter (22), which output is selected by the control of the processing unit (25), and after the lapse of output stabilisation time, the voltage at the output of the processing unit (25) corresponds to the new digital value E(n). In order to change the value of the output, a new digital value E(n+1) is applied to the input of the first converter (20), which output is now selected by the control of the processing unit, and after the lapse of output stabilisation time. The two converters (20,22) can have the same digital value at input, and the digital value E(n) is at the input of the first converter (20), which output is selected by the processing unit. The selection between the two converters is triggered by the arrival of a new sample E(n).
