Patent ID: 8195100
Filing Date: 2012-06-05
Classification: G06K

Abstract:
1. A transponder circuit with double clock extractor unit, said transponder circuit comprising an antenna coil connected to a modulator rectifier block to supply a rectified supply voltage on the basis of a radio-frequency signal picked up by the antenna coil at determined frequency and sufficient amplitude, wherein a terminal of the antenna coil is connected to the double clock extractor unit, and a control logic receiving a clock signal of the double clock extractor unit and supplying a modulation signal to the modulator rectifier block, wherein the double clock extractor unit comprises a first sensitive clock extractor and a second inverter clock extractor, and wherein the modulation signal is supplied to the double clock extractor unit to select the clock signal produced by the first clock extractor when the modulation signal is in a first status, or the clock signal produced by the second clock extractor when the modulation signal is in a second status wherein the first sensitive clock extractor has a low switching threshold below a switching threshold of the modulator rectifier block to rectify the alternating voltage of the antenna coil, and wherein the second inverter clock extractor has a high switching threshold equal to or higher than the threshold of the modulator rectifier block, wherein the first sensitive clock extractor comprises a comparator, of which a positive input is connected across one of the terminals of the antenna coil and a negative input is polarised by a reference voltage with a value below the threshold voltage of the modulator rectifier block in the order of 100 mV, wherein the output of the comparator supplies the clock signal of the first clock extractor, and wherein the second inverter clock extractor comprises at least a first inverter connected as input across the same terminal of the antenna coil as the first clock extractor.