U.S. Philips Corporation

Richard Morisson

Frederic Darthenay

Philippe Gandy

Stephane Barbu

Denis L Raoulx

Pieter P Vorenkamp

Fr&eacute;d&eacute;ric Darthenay

Interface circuit for a video camera

An A/D conversion device, for converting an analog input voltage Vin into a digital output signal encoded in N bits OUT(0:N-1), includes a first decoder (FNE) for generating the least significant bits OUT(0:K) of the output signal, and a second decoder (CRS) for generating signals which are representative of transitions to which the most significant bits OUT(i+1) of the output signal are to be submitted, for i=k to N-2. Each transition of the bit OUT(i+1) is signaled by signals referred to as antecedent signals A(i+1) and subsequent signals P(i+1), while an encoder (ENC) is provided for synchronizing each transition with a transition of the bit OUT(i) of the next lower weight.

A/D conversion device having synchronous output signals

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

An amplifying device has a decibel gain that evolves quasi-linearly as a function of the digital value of a control word C(O:M-1). The device includes: an amplifying stage with K amplifiers having mutually different decibel gains, the gain in decibels of each amplifier being a multiple of the same value G0; a switching stage with K switches; a gain-controlled amplifier having a gain which varies between 0 and G0 as a function of the value of the N least significant bits (C(O:N-1)) of the control word received at its digital input; and a decoder receiving a digital word including the (M-N) most significant bits (C(N:M-1)) of the control word. The decoder has K logic outputs controlling the K switches.

Digitally gain-controlled amplifying device, and camera using such a

The invention relates to a digitally gain-controlled amplifier including a transconductance stage provided with means for producing, at each of its N current outputs, a current (Itr) having a variable component which is representative of the analog input voltage. The amplifier also includes a switching stage comprising N switches each controlling the activation or deactivation of one of the N current outputs of the transconductance stage. Finally, the amplifier has a current/voltage conversion stage having one voltage output constituting the analog output of the amplifier and supplying a voltage which is representative of the currents received at its N current inputs.

Digitally gain-controlled amplifier, and camera using such an amplifier

An A/D converter in which an interpolation circuit (15, 16, 17, 18) makes weighted combinations of reference crossing signals (A/Ac,B/Bc) provided by an input circuit (100, 200), so as to obtain an expanded set of reference crossing signals (A/Ac+A1/Ac1 . . . A7/Ac7, B/Bc+B1/Bc1 . . . Bc7). The interpolation circuit (15, 16, 17, 18) is arranged to make at least one weighted combination of reference crossing signals with weighting factors which have a non-integer ratio so as to compensate for a non-linearity in the reference crossing signals (A/Ac,B/Bc). Accordingly, a better compromise is obtained between accuracy, on the one hand, and circuit complexity, on the other hand.

A/D converter with interpolation

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.

Circuit intended to supply a reference voltage

An integrated circuit comprising a current generator which is switchable to at least two modes. A first stage comprises a current mirror (T.sub.3, T.sub.4) having two branches. A differential pair second stage (T.sub.1, T.sub.2) is either in a balanced state (current output zero) or in an unbalanced state (current source R.sub.10, T.sub.10 supplying a current I.sub.1). In the balanced state a second current source (R.sub.20, T.sub.20) supplies a current which maintains the currents in the two branches of the current mirror constant.

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Caen, France

Richard Morisson