Transponder

• US 20050093680A1
• Filed: 11/27/2002
• Published: 05/05/2005
• Est. Priority Date: 12/24/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Cantatore, Eugenio
• Granted Patent: US 7,253,718 B2
• Time in Patent Office: Days
• US Class Current: 340/10.4
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

A identification transponder (IDT) for supplying an identification code to a base station (BS) varies an RF signal transmitted by the base station (BS) in a rhythm that corresponds to the identification code. The identification transponder (IDT) has identification code generation means (IDCG) for generating the identification code, rectifier means (RTF) for AC coupling with the base station (BS) for applying a supply voltage (V1) to the identification code generation means (IDCG), a modulation transistor (TM), voltage adaptation means (VADPT) for adapting the voltage levels of the identification code and for supplying the code with adapted voltage levels to a control terminal of the modulation transistor (TM), and further rectifier means (FRTF) for the aforementioned AC coupling to the base station (BS) for applying a separate supply voltage (V2) to the voltage adaptation means (VADPT). The modulation transistor (TM) may perform two tasks: the task of rectifying the RF signal, and the task of supplying a variable load to the rectifier means (RTF). The variable load varies in the rhythm. As a consequence, the input current of the rectifier means (RTF) is varied in the rhythm, which in its turn varies the RF signal. This variation in the RF signal is detected in the base station (BS).

Claims

1. A transponder (IDT) for supplying a code to a base station (BS) by varying a radio-frequency signal (RF) coming from the base station (BS) in a rhythm that corresponds to the code, the transponder (IDT) comprising identification code generation means (IDCG) for generating the code;

rectifier means (RTF) which are arranged for AC coupling with a radio-frequency signal (RF) for applying a supply voltage (V₁) to the generation means (IDCG), and which rectifier means (RTF) comprise at least one circuit acting as a rectifier;

a modulation transistor (TM) having a main current path, and comprising a control electrode which is coupled for the reception of the code for producing a variable load of the rectifier means (RTF) as a result of which the radio-frequency signal (RF) varies with said rhythm, at least one of the circuits acting as a rectifier comprising the main current path of the modulation transistor (TM);

voltage adaptation means (VADPT) for adapting the voltage levels of the code and for supplying the code with the adapted voltage levels to the control electrode of the modulation transistor (TM); and

further rectifier means (FRTF) for applying a separate supply voltage (V₂) to the voltage adaptation means (VADPT).

2. A transponder (IDT) as claimed in claim 1, characterized in that the voltage adaptation means (VADPT) comprise a series combination of a main current path of an adaptation transistor (T_adpt) and a resistive element (R), which series combination is coupled for the reception of the separate supply voltage (V₂), and where a control electrode of the adaptation transistor (T_adpt) is coupled for the reception of the code supplied by the identification code generation means (IDCG) and where a common junction (9) of the adaptation transistor (T_adpt) and the resistive element (R) is coupled with the control electrode of the modulation transistor (TM).

3. A transponder (IDT) as claimed in claim 1, characterized in that the AC coupling is a capacitive coupling (P1;

P3, P2;

P4) because the transponder (IDT) comprises a first contact pad (P1) for a capacitive coupling with a first contact pad (P3) of the base station (BS), and because the transponder (IDT) comprises a second contact pad (P2) for capacitive coupling with a second contact pad (P4) of the base station (BS), and in that the rectifier means (RTF) comprise a circuit (D1) acting as a rectifier, not being the modulation transistor (TM), which is coupled between the first contact pad (P1) of the transponder (IDT) and the second contact pad (P2) of the transponder (IDT), and in that the main current path of the modulation transistor (TM) is connected in series with a supply terminal (1, 2) of the identification code generation means (IDCG) and in that the further rectifier means (FRTF) are arranged for being coupled to the radio-frequency signal (RF) via the capacitive coupling (P1;

P3, P2;

P4).

4. A transponder (IDT) as claimed in claim 1, characterized in that the AC coupling is a capacitive coupling (P1;

P3, P2;

P4) because the transponder (IDT) comprises a first contact pad (P1) for capacitive coupling with a first contact pad (P3) of the base station (BS), and because the transponder (IDT) comprises a second contact pad (P2) for capacitive coupling with a second contact pad (P4) of the base station (BS), and in that the main current path of the modulation transistor (TM) is coupled between the first contact pad (P1) of the transponder (IDT) and the second contact pad (P2) of the transponder (IDT), and in that the rectifier means (RTF) comprise a circuit acting as a rectifier (D2), not being the modulation transistor (TM), which is coupled in series with a supply terminal (1, 2) of the generation means (IDCG), and in that the further rectifier means (FRTF) are arranged for being coupled with the radio-frequency signal (RF) via the capacitive coupling (P1;

P3, P2;

P4).

5. A transponder (IDT) as claimed in claim 1, characterized in that the AC coupling is an inductive coupling (L1, L2) because the transponder (IDT) comprises a coil (L1) for inductive coupling with a coil (L2) of the base station (BS), which coil (L1) is electrically coupled with the rectifier means (RTF) and with the further rectifier means (FRTF) for the reception of the radio-frequency signal (RF), and in that the main current path of the modulation transistor (TM) is coupled in series with a supply terminal (1, 2) of the identification code generation means (IDCG).

6. A transponder (IDT) as claimed in one of the preceding claims, characterized in that the transponder comprises electronic components which are mainly manufactured from one or more organic materials.

7. A transponder (IDT) as claimed in claim 6, characterized in that at least one of the organic materials is a polymer.