Circuit arrangement and method for phase modulation in a backscattering transponder
First Claim
1. A circuit arrangement adapted to vary an input impedance of an input circuit of a backscattering transponder to produce a phase modulation of a backscattered signal, said circuit arrangement comprising:
- a varactor that has first and second varactor terminals by which said varactor is connected in the input circuit;
first and second voltage sources;
a switching arrangement that is connected between said voltage sources and at least one of said varactor terminals, and that is adapted to selectively conductively connect and disconnect said voltage sources relative to said at least one of said varactor terminals; and
a control unit that has at least one control output connected to at least one control input of said switching arrangement, and that is adapted to control said switching arrangement to selectively conductively connect said voltage sources to said at least one of said varactor terminals depending on a phase position that is to be provided in the phase modulation.
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Accused Products
Abstract
A circuit arrangement for phase modulation in an input circuit of a backscattering transponder includes a varactor and at least one capacitor connected in series between two antenna terminals, and at least two voltage sources selectively connected through at least two switches to at least one terminal of the varactor. A control unit selectively opens and closes the switches in response to the data to be phase-modulated onto the backscattered signal. By selectively connecting the different voltage values of the respective voltage sources to the varactor terminal(s) through the switches, the capacitance of the varactor and correspondingly the input impedance of the input circuit are thereby varied, so as to provide respective different phase positions of the phase modulation.
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Citations
18 Claims
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1. A circuit arrangement adapted to vary an input impedance of an input circuit of a backscattering transponder to produce a phase modulation of a backscattered signal, said circuit arrangement comprising:
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a varactor that has first and second varactor terminals by which said varactor is connected in the input circuit;
first and second voltage sources;
a switching arrangement that is connected between said voltage sources and at least one of said varactor terminals, and that is adapted to selectively conductively connect and disconnect said voltage sources relative to said at least one of said varactor terminals; and
a control unit that has at least one control output connected to at least one control input of said switching arrangement, and that is adapted to control said switching arrangement to selectively conductively connect said voltage sources to said at least one of said varactor terminals depending on a phase position that is to be provided in the phase modulation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of producing a phase modulation in a backscattering transponder having a varactor with first and second varactor terminals in an input circuit of said transponder, and having first and second voltage sources, said method comprising the steps:
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a) providing control information dependent on a respective phase position of said phase modulation that is to be produced;
b) producing a first voltage with said first voltage source;
c) producing a second voltage with said second voltage source;
d) in response to said control information and dependent on said respective phase position, selectively applying at least one of said first voltage and said second voltage as a control voltage to at least one of said varactor terminals;
e) in response to and dependent on said control voltage, varying a capacitance of said varactor so as to correspondingly vary an input impedance of said input circuit, which produces said phase modulation. - View Dependent Claims (16, 17, 18)
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Specification