Transponder

• US 9,335,744 B2
• Filed: 09/08/2014
• Issued: 05/10/2016
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Akbari-Dilmaghani, Rahim
• Primary Examiner(s): HUNNINGS, TRAVIS R
• Application Number:
  US14/480,471
• Publication Number:
  US 20150022318A1
• Time in Patent Office: 610 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G05B 1/01 electric
• CPC Class Codes: G06K 19/07792 the antenna adapted for extending in three dimensions
• CPC Class Codes: H01Q 1/3241 particular used in keyless entry systems
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A transponder for receiving a wireless electromagnetic query signal and for transmitting a wireless electromagnetic response signal with a coil acting as a first antenna for generating a first wired electrical incoming signal from the query signal and with at least one further coil acting as an antenna for generating a further wired electrical incoming signal from the query signal, and wherein an axis of the first coil and an axis of the further coil are differently aligned in space, and wherein the coils are assigned at least one means for limiting the voltage of the respective incoming signals, and wherein the incoming signals are routed, respectively, via a first full-wave rectifier for generating a rectified incoming signal, and wherein the rectified incoming signals are routed, respectively, to a current-controlled source of current for generating a current signal that corresponds to the respective incoming signal, and wherein the current signals are routed, respectively, to a peak value of current detector for generating a peak value of current signal, and wherein the peak value of current signals are routed to a comparison arrangement for comparing the generated peak value of current signals, and wherein the comparison arrangement is configured for generating a control signal that indicates the strongest peak value of current signal of the generated peak value of current signals.

Claims

1. A transponder, comprising:

a first coil coupled to receive a wireless electromagnetic query signal, the first coil generates a first wired electrical incoming signal from the query signal;

at least one additional coil coupled to receive the wireless electromagnetic query signal, the at least one additional coil generates a second wired electrical incoming signal from the query signal, wherein a first axis of the first coil and a second axis of the at least one additional coil having different spatial alignments,

at least one full-wave rectifier, coupled to the first coil and the at least one further coil, the at least one full-wave rectifier generating a first rectified incoming signal and a second rectified incoming signal from the first and second wired electrical incoming signal;

a comparator that compares a first peak associated with the first rectified incoming signal and a second peak associated with the second rectified incoming signal, the comparator identifies a larger peak between the first and second peaks.

2. The transponder of claim 1 further comprising a first limiter that limits a first voltage level on the first wired electronic incoming signal.

3. The transponder of claim 2 further comprising a second limiter that limits a second voltage level on the second wired electronic incoming signal.

4. The transponder of claim 1 further comprising at least one current-controlled source of current coupled to the at least one full-wave rectifier, the at least one current-controlled source of current generating a first current signal and a second current signal that correspond to the first and second rectified incoming signals.

5. The transponder of claim 4 wherein the at least one current-controlled source of current comprises at least one current mirror that generates, in addition to the first and second current signals, a first mirrored current and a second mirrored current, and wherein a summing element is provided for summing up the first and second mirrored current and generating a pulsating composite signal that has a frequency doubling the frequency of the wireless electromagnetic query signal.

6. The transponder of claim 5 further comprising a comparator that compares the pulsating composite signal to a reference signal to generate a first clocking signal that has a frequency doubling the frequency of the wireless electromagnetic query signal.

7. The transponder according to claim 6 wherein the first clocking signal is converted to a second clocking signal having a lower frequency by a frequency divider.

8. The transponder of claim 7 further wherein the frequency divider is a frequency-halving divider such that the frequency of the second clocking signal is equal to the frequency of the wireless electromagnetic query signal.

9. The transponder of claim 4 further comprising at least one current detector coupled to the at least one current-controlled source of current, the at least one current detector detects a first peak value of current signal and a second peak value of current signal that are associated with the peak values of the first and second current signals.

10. The transponder of claim 1 wherein the full-wave rectifier generating a supply voltage for the purpose of limiting the voltages of the first and second wired electrical incoming signals.

11. The transponder of claim 1 further comprising a voltage smoother coupled to receive the first and second wired electronic incoming signals, the voltage smoother reduces at least one amplitude peak on the first or second wired electronic incoming signals.

12. The transponder of claim 1 wherein the at least one additional coil is a single coil, the first coil being associated with a first input on the comparator and the at least one additional coil being associated with a second input on the comparator.

13. The transponder of claim 12 wherein the comparator generates a control signal identifying a preference between the first coil and the at least one additional coil.

14. The transponder of claim 1 wherein the at least one additional coil includes at least two coils such that more than two coils are included in the transponder, the comparator comprises a plurality of comparators and a logic circuit, each comparator comparing two of a plurality of peak values of a plurality of current signals, output signals of the plurality of comparators being processed in the logic circuit to generate the control signal.

15. The transponder of claim 1 wherein the transponder is at least in part manufactured as a CMOS-integrated circuit.

16. A method for selecting a preferred wireless signal received at a multi-coil transponder, the method comprising:

receiving a first wireless signal at a first coil and generating a corresponding first electrical signal;

receiving at least one additional wireless signal at least one additional coil and generating a corresponding at least one additional electrical signal, the at least one additional coil having a different axis spatial alignment than the first coil;

limiting the voltage of the first and at least one additional electrical signal;

rectifying the first and at least one additional electrical signal;

detecting a first peak on the first rectified electrical signal and a second peak on the at least one additional rectified electrical signal;

comparing the first and second peaks; and

selecting a preferred signal based on the comparison of the first and second peaks.

17. The method of claim 16 further comprising the step of generating a first current derived from the first electrical signal and a second current derived from the at least one additional electrical signal, the first and second currents being supplied by a single current-controlled source.

18. The method of claim 16 further comprising the step of smoothing the first rectified electrical signal and the at least one additional rectified electrical signal.

19. The method of claim 16 further comprising the step of switching a transmission channel within the transponder based on the preferred signal.

20. The method of claim 16 wherein the at least one additional coil is a second coil and a comparator compares the first and second peaks.