Em Microelectronic-marin Sa

Nicolas Pillin

David A Kamp

Goran Stojanovic

Tony Ghueldre

An envelope detector circuit, suitable for use in RFID tags, includes a voltage doubler circuit and a biasing voltage generating circuit which comprises components matched respectively to rectifying components of the voltage doubler circuit. A rectifying component of this voltage doubler circuit is formed by a transistor controlled by the biasing voltage generating circuit which provides a biasing voltage to a control gate of this transistor, the biasing voltage generating circuit being arranged so as to permit a determined forward biasing current to flow through the transistor and further rectifying elements of the voltage doubler circuit. This embodiment provides fast, highly sensitive detection of envelope waveforms in input signals. Thanks to the matched rectifying components, efficiency variations due to variations in manufacturing process can be eliminated. The envelope detector circuit is further arranged for maintaining a stable detection independent of variations in temperature.

Envelope detector circuit

A RFID transponder includes an electronic circuit and an antenna, the electronic circuit being integrated in a p-type substrate and comprising a modulator formed by a PMOS transistor whose drain, electrically connected to a pad of the antenna, and source, connected to the ground of the electronic circuit, are arranged in an n-type well provided in the p-type substrate. The PMOS transistor has a gate driven by a driving circuit which is arranged for providing at least a negative voltage, this negative voltage being low enough for turning on this PMOS transistor in response to a control signal provided by a logical unit of the electronic circuit.

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St-Sulpice, Switzerland

Nicolas Pillin