Quality adjustment of a receiving circuit

• US 9,148,189 B2
• Filed: 01/16/2008
• Issued: 09/29/2015
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Froitzheim, Herbert
• Primary Examiner(s): SMALL, NAOMI J
• Application Number:
  US12/525,118
• Publication Number:
  US 20100127820A1
• Time in Patent Office: 2,813 Days
• Field of Search: 340/5.2
• US Class Current: 1/1
• 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
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H

Abstract

A receiving circuit for a communication unit of an access device has a resonance circuit (1) with a receiving coil (L) for converting a magnetic induction into electrical current, and a capacitor (C). The receiving circuit (10) further has a first resistor (R1) and a switching element (3) designed for controllably connecting and disconnecting the first resistor (R1) to the resonance circuit (1). The receiving circuit electrically connects the resonance circuit (1) to the first resistor (R1) when the circuitry of the resonance circuit (1) changes from a first circuitry (7) to a second circuitry (8), and electrically disconnects the first resistor (R1) from the resonance circuit (1) when the circuitry of the resonance circuit (1) changes from the second circuitry (8) to the first circuitry (7).

Claims

1. A receiving circuit for a communication device of an access arrangement, the receiving circuit comprising:

a resonant circuit comprising;

a receiving coil for converting magnetic induction caused by received radio signals into electrical current, and

a capacitor,

the resonant circuit configured to generate a resonant circuit output signal representing a field strength of the received radio signals,

a first resistor;

field strength measurement circuitry configured to measure the field strength of the received radio signals;

telecommunication processing circuitry configured to perform telecommunication-based processing of the resonant circuit output signal; and

switching circuitry operable to switch the receiving circuit between;

a field strength measurement state in which the resonant circuit is connected to the field strength measurement circuitry and the first resistor, the first resistor damping a magnitude of the resonant circuit output signal to allow measurement of the field strength of received radio signals, by the field strength measurement circuitry, based on the dampened resonant circuit output signal; and

a signal processing state in which the resonant circuit is (a) disconnected from the field strength measurement circuitry and the first resistor and (b) connected to the telecommunication processing circuitry, to thereby allow telecommunication-based processing, by the telecommunication processing circuitry, of the resonant circuit output signal undamped by the resistor,

such that the resonant circuit is connected to the field strength measurement circuitry in the field strength measurement state of the receiving circuit and disconnected from the field strength measurement circuitry in the signal processing state of the receiving circuit.

2. The receiving circuit according to claim 1, wherein the receiving coil and the capacitor are arranged in a parallel connection.

3. The receiving circuit according to claim 1, wherein the receiving coil and the capacitor are arranged connected in series.

4. The receiving circuit according to claim 1, wherein the switching circuitry has a first switched state for connecting the resonant circuit and first resistor in a parallel connection.

5. The receiving circuit according to claim 1, wherein the switching circuitry has a first switched state for connecting the resonant circuit and first resistor in a series connection.

6. The receiving circuit according to claim 1, wherein the switching circuitry has a second switched state for disconnecting an electrical connection between the resonant circuit and the first resistor.

7. The receiving circuit according to claim 1, wherein the resonant circuit comprises a further resistor which is connected in parallel or in series with at least one of the receiving coil and the capacitor.

8. A communication device for an access arrangement having a receiving circuit as claimed in claim 1.

9. An access arrangement comprising:

a first communication device for emitting at least one interrogation signal in the inductive frequency range;

a second communication device having a receiving circuit according to claim 1 for receiving and processing the interrogation signal in the inductive frequency range.

10. The access arrangement according to claim 9, wherein the switching element has a first switched state for connecting the resonant circuit and first resistor in a parallel connection.

11. The access arrangement according to claim 9, wherein the switching element has a first switched state for connecting the resonant circuit and first resistor in a series connection.

12. The access arrangement according to claim 9, wherein the switching element has a second switched state for disconnecting an electrical connection between the resonant circuit and the first resistor.

13. The access arrangement according to claim 9, wherein the resonant circuit includes a receiving coil and/or the capacitor, and wherein the resonant circuit comprises a further resistor which is connected in parallel or in series with at least one of the receiving coil and the capacitor.

14. A method for changing the quality of a resonant circuit of a receiving circuit, the method comprising:

receiving radio signals at the resonant circuit, and generating a resonant circuit output signal representing a field strength of the received radio signals,

operating the receiving circuit in a field strength measurement state in which;

the resonant circuit is electrically connected to (i) field strength measurement circuitry configured to measure the field strength of the received radio signals and (ii) a first resistor that dampens a magnitude of the resonant circuit output signal, and

the field strength of received radio signals is measured by the field strength measurement circuitry based on the dampened resonant circuit output signal; and

the receiving circuit automatically switching to a signal processing state in which;

the resonant circuit is (a) electrically disconnected from (i) the field strength measurement circuitry and (ii) the first resistor that dampens the magnitude of the resonant circuit output signal, and (b) electrically connected to telecommunication processing circuitry configured to perform telecommunication-based processing of the resonant circuit output signal, and

the resonant circuit output signal undamped by the resistor is processed by the telecommunication processing circuitry,

such that the resonant circuit is connected to the field strength measurement circuitry in the field strength measurement state of the receiving circuit and disconnected from the field strength measurement circuitry to the signal processing state of the receiving circuit.

15. The method according to claim 14, wherein connecting and disconnecting of the first resistor is performed using a switching element.

16. The method according to claim 15, wherein the switching element has a first switched state for connecting the resonant circuit and first resistor in a parallel connection.

17. The method according to claim 15, wherein the switching element has a first switched state for connecting the resonant circuit and first resistor in a series connection.

18. The method according to claim 15, wherein the switching element has a second switched state for disconnecting an electrical connection between the resonant circuit and the first resistor.

19. The method according to claim 14, wherein the resonant circuit includes a receiving coil and/or the capacitor, and wherein the resonant circuit comprises a further resistor which is connected in parallel or in series with at least one of the receiving coil and the capacitor.