U.S. Philips Corporation

Philippe Gandy

Richard Morisson

Frederic Darthenay

Stephane Barbu

An A/D conversion device includes: an amplifier AMP provided with regulating means controlled by a control signal OC or GC for adjusting the value of its output voltage V2, and

A/D conversion device provided with a calibration arrangement

A/D conversion device provided with a gain calibration arrangement

The circuit, arranged between a source of higher voltage (VCC) and a source of lower voltage (ground), comprises an analog/digital converter (ADC) which has a resistor ladder (RL) connected between a top terminal (Vtop), a bottom terminal (Vbot) for supplying a series of reference voltages. According to the invention, this circuit includes a bias generator arrangement formed by a resistor (Rmid) connected on one side to the supply voltage source and on the other side to a reference current source (Ip0), and automatic control means (A2) for controlling a variable impedance element (T5) inserted between the connection (Vbot) at the bottom of the ladder and ground, which automatic control means are suitable for controlling the voltage (FS) at the terminals of the resistor ladder.

Analog/digital converter with automatic control for controlling offset

The invention relates to a circuit intended to supply a reference voltage comprising a voltage generator (REF) provided with a supply terminal and an output for supplying a voltage having a given nominal value (V.sub.R) and comprising a differential amplifier (A), fed by a first supply voltage, whose non-inverting input is connected to the output of the voltage generator (REF). An output of the differential amplifier (A) is connected to an input of a follower stage (T) through a controlled switching device (1), the follower stage (T) having its input connected to the first supply voltage through a first resistor (R.sub.1) and having its output, which supplies the said reference voltage (V.sub.D), connected on the one hand to the inverting input of the differential amplifier (A) through a divider bridge and on the other hand to the supply termianl of the voltage generator (REF). A control circuit (C) of the switching device is operated so as to receive at least the supply voltage in such a manner that the switching device (1) is closed when the supply voltage reaches a threshold for which both the voltage generator and the differential amplifier are in a nominal operating zone.

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Thaon, France

Philippe Gandy