ELECTRONIC CIRCUIT AND METHOD FOR DETERMINING AN IMPEDANCE

• US 20120286807A1
• Filed: 07/30/2012
• Published: 11/15/2012
• Est. Priority Date: 01/28/2010
• Status: Active Grant

• Current Assignee: Junghans Microtec GmbH
• Original Assignee: Junghans Microtec GmbH
• Inventors: KÖLBLI, BERTRAM
• Granted Patent: US 9,188,613 B2
• Time in Patent Office: Days
• US Class Current: 324/655
• CPC Class Codes: G01R 25/00 Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00
• CPC Class Codes: G01R 27/28 Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response in line transmission systems H04B3/46
• CPC Class Codes: G01R 29/023 Measuring pulse width
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: H02H 3/382 involving phase comparison between current and voltage or between values derived from current and voltage

Abstract

An electronic circuit is arranged in an external programming device and is used for contactless programming of a circuit to be programmed. The electronic circuit has a series resonant circuit that includes a transmitter coil and a capacitor. The transmitter coil of the series resonant circuit is used for inductive coupling to a receiver coil in the circuit to be programmed. For the purpose of evaluating the impedance that actually exists in the circuit to be programmed, there is provided a device for determining the value of the impedance from a phase difference between the control voltage of the series resonant circuit and the capacitor voltage of the series resonant circuit.

Claims

1. An electronic circuit in an external programming device and configured for contactless programming of a circuit to be programmed, the electronic circuit comprising:

a series resonant circuit including a transmitter coil and a capacitor connected in series;

said transmitter coil of the series resonant circuit being disposed for inductive coupling to a receiver coil of the circuit to be programmed; and

a device connected to said series resonant circuit and configured for determining, from a phase difference between a control voltage of said series resonant circuit and a capacitor voltage of said series resonant circuit, an actual impedance existing in the circuit to be programmed.

2. The electronic circuit according to claim 1, wherein said device for determining the actual impedance comprises an equivalence element having a first input receiving a control voltage, pulsed at a carrier frequency, a second input receiving the capacitor voltage of said series resonant circuit, and an output, and said device for determining the actual impedance further comprises means for determining a duty factor at said output of said equivalence element.

3. The electronic circuit according to claim 2, wherein said equivalence element is an EXOR gate or an EXNOR gate.

4. The electronic circuit according to claim 2, wherein the capacitor voltage is fed to said second input of said equivalence element via a level converter.

5. The electronic circuit according to claim 2, which comprises a frequency generator and a frequency divider connected to said output of said frequency generator for generating the carrier frequency.

6. The electronic circuit according to claim 5, wherein said frequency divider has a divider factor of 2^n-1.

7. The electronic circuit according to claim 2, wherein said means for determining the duty factor is a binary up/down counter, said up/down counter having an up/down input connected to said output of said equivalence element, and said up/down counter is clocked by a counting clock that equals a multiple of the carrier frequency.

8. The electronic circuit according to claim 7, wherein the counting clock equals 2^n-1 times the carrier frequency and has an n-bit wide output.

9. The electronic circuit according to claim 7, wherein an output of said up/down counter is connected to an input of a latch, and said latch has a further input connected to said first input of said equivalence element and configured to trigger a data transfer.

10. The electronic circuit according to claim 9, which further comprises a delay element connected between said first input of said equivalence element and a reset input of said up/down counter, and wherein said delay element is operated at the carrier frequency.

11. The electronic circuit according to claim 9, wherein said latch has an output connected to a microprocessor.

12. The electronic circuit according to either of claim 11, which further comprises a delay element connected between said first input of said equivalence element and a reset input of said up/down counter, and wherein said delay element is operated at the carrier frequency, and said delay element has an output connected to an input of the microprocessor, said input determining a validity of data at the input port.

13. A method of determining an impedance that actually exists in a programmable circuit, wherein the programmable circuit includes a receiver coil for contactless coupling with an electronic circuit containing a series resonant circuit and wherein the series resonant circuit includes a transmitter coil and a capacitor, the method which comprises:

inductively coupling the transmitter coil of the series resonant circuit to the receiver coil of the programmable circuit;

measuring a phase difference between a control voltage of the series resonant circuit and a capacitor voltage of the series resonant circuit; and

determining from the phase difference the impedance that actually exists in the programmable circuit.

14. The method according to claim 13, which comprises determining the phase difference by logically combining the control voltage, pulsed at a carrier frequency, and the capacitor voltage of the series resonant circuit with an equivalence element, and analyzing a duty factor of a signal at an output of the equivalence element.

15. The method according to claim 14, wherein the equivalence element is an EXOR gate or an EXNOR gate.

16. The method according to claim 13, which comprises generating the carrier frequency with a frequency generator and a frequency divider connected to an output of the frequency generator.

17. The method according to claim 16, wherein the frequency divider has a divider factor of 2^n-1.

18. The method according to claim 13, which comprises determining the duty factor of the signal at the output of the equivalence element by way of an up/down counter, inputting the signal at the output of the equivalence element to an up/down input of the up/down counter, and clocking the up/down counter by a counting clock that equals a multiple of the carrier frequency.

19. The method according to claim 18, wherein the up/down counter is a binary counter.

20. The method according to claim 18, which comprises clocking the up/down counter at 2^n-1 times the carrier frequency and providing the up/down counter with an n-bit wide output.