Analogue/digital conversion device having a constant differential non-linearity

摘要

The device comprises a ladder resistor (LAD) for the provision of reference voltages. There is a set of amplifiers (A) comparing the input signal (Vin) to the reference voltages, and a set of detectors (DET) of latch circuit type signaling the zero-passages of each signal at outputs of amplifiers. A binary encoder (ENC) delivers a signal with a value dependent on the zero-passages. There is an amplifier gain control to make the amplifier gain and that of the device mutually proportional. The non-linearity differential remains constant and does not change with the gain variation. The control comprises a current source (I1) connected in series with the ladder resistor and controlled by debiting a current in proportion to the control signal (GC). The control also involves each amplifier (A) having a control input receiving the control signal (GC), and the gain of each amplifier is arranged to be proportional to the signal received at the control input. Each amplifier (A) includes a differential pair of transistors and a current source with control input. The control also uses a comparator (DEC) for effecting a comparison of the output signal from demultiplexer (DMX) to a predetermined value from a memory store (CODE), and for delivering the control signal (GC). In the phase of calibration, a signal (CAL) is input to the control of demultiplexer (DMX).