Communication arrangement comprising powerful integrated amplitude-modulation means

A communication arrangement (1) by which data (DA) can be transmitted to a transponder (2), comprising:

• a data source (5) for providing the data (DA),
• a carrier signal generator (6) for generating a carrier signal (CS), modulation means (7) for modulating the carrier signal (CS) in accordance with the data (DA) to produce a modulated carrier signal (CSM), and
• transmitting means (8) having a nominally constant input resistance (9) responsive to the modulated carrier signal (CSM)
• wherein the modulation means (7) includes an output resistance (10) which together with the input resistance (9) of the transmitting means (8) forms a resistance network (11), characterized in that:
• the output resistance (10) can be changed and resistance change means (25) are used for changing the output resistance (10) of the modulation means (7) in accordance with the data (DA),
• wherein the changeable output resistance (10) of the modulation means (7) can be combined from a first partial resistance (12A) and a second partial resistance (12B) and in that switching means (15, 16, 19 and 20) are provided for connecting the two partial resistances (12A, 12B) in parallel, and
• wherein at least one of the two partial resistances (12A, 12B) is realized by means of at least one driver (26, 27;
• 39, 40, 41, 42), while the driver (26, 27;
• 39, 40, 41, 42) has a transistor (28, 29, 33, 34;
• 44, 46, 48, 50) on its output side, wherein said transistor can be driven to a switching operation in which a turned-on transistor (28, 29, 33, 34;
• 44, 46, 48, 50) forms a basic resistance connected in a parallel combination to the first or second partial resistance (12A, 12B).