Alcatel

Alcatel Alsthom Compagnie Generale D'electricite

Jean-Philippe Robert Cornil

Filip Marcel Louagie

Rudi Verbist

Philippe Guillaume Dobbelaere

Zhong Yuan Chang

Francedillaois Jeanjean

The invention relates to a method for selecting a sequence of cells of current sources inside a cell matrix structure of a digital-analog converter and also to the corresponding converter. Symmetries are used with regard to the centre (C) of a rectangular or preferably square matrix structure, with regard to a symmetry point (S) located at a quarter of the length of a diagonal (D1) from the centre and with regard to one of the two mean perpendiculars (M1) of the structure for selecting the mapping areas (1, 2, . . . ) for the consecutive cells.

Method for selecting a sequence of cells inside a bidimensional matrix

A differential output amplifier arrangement (DOA) including two operational amplifiers (OA1,OA2), each having a feedback resistor (R2,R20), and which are coupled by a first resistor (R1) between similar polarity type input terminals, further includes a pair of output resistors (R3,R30), coupled between respective output terminals (OUT1,OUT2), of each respective operational amplifier, and corresponding respective output terminals (ZOUT1,ZOUT2) of said arrangement, and a pair of resistors (R4,R40), each of which is cross-coupled between a respective output terminal of said arrangement (ZOUT1,ZOUT2) and one of the two similar polarity type, by the first resistor coupled, input terminals (INN2,INN1) of the respective cross-coupled operational amplifier. A method for adapting the output impedance of a differential output amplifier arrangement is described as well.

Differential output amplifier arrangement and method for tuning the

A low noise amplifier structure based on a Differential Difference Amplifier (DDA1) having a differential output (outp, outn) and two differential pairs of input terminals (N1, P1; N2, P2). The input signal (V.sub.IN) is applied to terminals (N2, P1) which belong to different differential pairs. In this way, none of the differential pairs receives a high input signal, and hence none of them cause unacceptable harmonic distortion. The dynamic input range is thus high. The gain of the structure is determined by a resistive circuit (R2a, R2a'; R2b, R2b') coupled to the remaining terminals (N1, P2) of the differential pairs. The common mode of these remaining terminals (N1, P2) is, independently from the output common mode, biased at the input common mode via a common mode feedback circuit (DDA2; GL1, GH1, GH3, R2a, R2a'; GL2, GH2, GH4, R2b, R2b') based on a second differential difference amplifier (DDA2). Some switching elements (GL1, GH1, GH3; GL2, GH2, GH4) allow the gain to be programmed and prevent the common mode feedback circuit from injecting differential noise if the gain is high. The structure is adapted to amplify signals of 1 Vpp with acceptably low distortion.

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Edingen, Belgium

Jean-Philippe Robert Cornil