Testing resonant sensor circuits using signal sources and controllable resistors

Patent metadata

Field	Value
Publication number	US-2016223607-A1
Application number	US-201514611752-A
Country	US
Kind code	A1
Filing date	Feb 2, 2015
Priority date	Feb 2, 2015
Publication date	Aug 4, 2016
Grant date	—

Abstract

A test system (and methodology) suitable for testing a resonant sensor circuit configured to drive a sensor resonator with a negative resistance. Example embodiments include a test sensor resonator setup configured to simulate a sensor resonator with a selectable loss factor Rs, and includes, in a single-ended configuration, a first oscillator signal source that generates a first oscillation signal, coupled to a first controllable resistor that provides a controlled resistance R 1 that simulates a selectable sensor resonator loss factor Rs, which together generate a first oscillation voltage signal based on the controlled resistance R 1 . A DUT resonant sensor circuit is coupled to receive the first oscillation voltage signal at a first input, and generate a negative resistance −Ra that substantially counterbalances the resistance R 1 (corresponding to sustained oscillation). A differential configuration includes first and second oscillator signal sources, coupled to first and second controllable resistors R 1 and R 2.

First claim

1 . A test system suitable for testing a resonant sensor circuit configured for operation with a sensor resonator characterized by a loss factor Rs, the resonant sensor circuit configured to monitor resonator oscillation voltage, and to drive the sensor resonator with a negative resistance controlled to sustain resonator oscillation, comprising:
a test sensor resonator setup configured to simulate a sensor resonator with a selectable loss factor Rs, and including
a first oscillator signal source that generates a first oscillation signal, coupled to
a first controllable resistor that provides a controlled resistance R 1 that simulates a selectable sensor resonator loss factor Rs,
the first oscillator signal source and the first controllable resistor configured to generate a first oscillation voltage signal based on the controlled resistance R 1 ;
a device-under-test (DUT) resonant sensor circuit:
coupled to receive the first oscillation voltage signal at a first input; and
configured to generate, in response to the first oscillation voltage signal, a negative resistance −Ra that substantially counterbalances the resistance R 1 corresponding to a state of sustained oscillation at the first input.

2 . The system of claim 1 :
wherein the test sensor resonator setup further includes:
a second oscillator signal source that generates a second oscillation signal anti-phase to the first oscillation signal, coupled to
a second controllable resistor that provides a controlled resistance R 2 that simulates the selectable sensor resonator loss factor Rs;
wherein the first and second anti-phase oscillator signal sources and controlled resistances R 1 and R 2 are configured to generate differential first and second oscillation voltage signals at differential first and second inputs to the DUT resonant sensor circuit; and wherein the DUT resonant sensor circuit is configured to generate, in response to the differential first and second oscillation voltage signals, the negative resistance −Ra that substantially counterbalances the resistances R 1 and R 2 .

3 . The system of claim 1 , wherein the DUT resonant sensor circuit is configured for single-ended input, and wherein a boundary condition R 1 <−Ra is used for stability.

4 . The system of claim 2 , wherein a boundary condition (2*R 1 =2*R 2 )<−Ra is used for stability.

5 . The system of claim 1 , wherein the test sensor resonator setup further includes a first series coupling capacitor between the first controllable resistor and the first input to the DUT resonant sensor circuit, configured with an AC impedance that is substantially less than R 1 −Ra.

6 . The system of claim 2 , wherein the test sensor resonator setup further includes first and second series coupling capacitors between respectively the first and second controllable resistors, and the differential first and second inputs to the DUT resonant sensor circuit, both configured with an AC impedance that is substantially less than 2*R 1 −Ra.

7 . The system of claim 1 , wherein the DUT resonant sensor circuit comprises:
a resonant inductive sensor circuit configured for operation with a sensor LC resonator; and wherein the wherein the DUT resonant sensor circuit is configured to generate the negative resistance −Ra by controlling the average amplitude of the first oscillation voltage signal.

8 . A method suitable for testing a resonant sensor circuit configured for operation with a sensor resonator characterized by a loss factor Rs, the resonant sensor circuit configured to monitor resonator oscillation voltage, and to drive the sensor resonator with a negative resistance controlled to sustain resonator oscillation, comprising:
generating a first oscillation voltage signal with a first oscillator signal source, coupled to a first controllable resistor that provides a controlled resistance R 1 that simulates a selectable sensor resonator loss factor Rs; thereby simulating a sensor resonator with a selectable loss factor Rs; receiving the first oscillation voltage signal at a first input to a device-under-test (DUT) resonant sensor circuit; and operating the DUT resonant sensor circuit to generate, in response to the first oscillation voltage signal, a negative resistance −Ra that substantially counterbalances the resistance R 1 corresponding to a state of sustained oscillation at the first input to the DUT resonant sensor circuit.

9 . The method of claim 8 :
further comprising generating a second oscillation voltage signal with a second oscillator signal source that is anti-phase to the first oscillation signal source, and a second controllable resistor that provides a controlled resistance R 2 that simulates the selectable sensor resonator loss factor Rs; wherein the first and second anti-phase oscillator signal sources and controlled resistances R 1 and R 2 generate differential first and second oscillation voltage signals at differential first and second inputs to the DUT resonant sensor circuit; and wherein the DUT resonant sensor circuit generates, in response to the differential first and second oscillation voltage signals, the negative resistance −Ra that substantially counterbalances the resistances R 1 and R 2 .

10 . The method of claim 8 , wherein the DUT resonant sensor circuit is configured for single-ended input, and wherein a boundary condition R 1 <−Ra is used for stability.

11 . The method of claim 9 , wherein a boundary condition (2*R 1 =2*R 2 )<−Ra is used for stability.

12 . The method of claim 8 , further including a first series coupling capacitor between the first controllable resistor and the first input to the DUT resonant sensor circuit, configured with an AC impedance that is substantially less than R 1 −Ra.

13 . The method of claim 9 , further including first and second series coupling capacitors between respectively the first and second controllable resistors, and the differential first and second inputs to the DUT resonant sensor circuit, both configured with an AC impedance that is substantially less than 2*R 1 −Ra.

14 . The method of claim 8 , wherein the DUT resonant sensor circuit is a resonant inductive sensor circuit configured for operation with a sensor LC resonator, and configured to generate the negative resistance −Ra by controlling the average amplitude of the first oscillation voltage signal.

15 . A test system suitable for testing a resonant sensor circuit configured for operation with a sensor resonator characterized by a loss factor Rs, the resonant sensor circuit configured to monitor resonator oscillation voltage, and to drive the sensor resonator with a negative resistance controlled to sustain resonator oscillation, comprising:
a test sensor resonator setup configured to simulate a sensor resonator with a selectable loss factor Rs, and including
a first oscillator signal source that generates a first oscillation signal, coupled to a first controllable resistor that provides a controlled resistance R 1 that simulates a selectable sensor resonator loss factor Rs,
a second oscillator signal source that generates a second oscillation signal anti-phase to the first oscillation signal, coupled to a second controllable resistor that provides a controlled resistance R 2 that simulates the selectable sensor resonator loss factor Rs;
the first and second anti-phase oscillator signal sources and controlled resistances R 1 and R 2 are configured to generate differential first and second oscillation voltage signals at differential first and second inputs to the DUT resonant sensor circuit; and a device-under-test (DUT) resonant sen

Assignees

• Texas Instruments Inc

Inventors

• Paclibon Frederick
• Reitsma George P

Classifications

• G01R27/26

  Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants {; Measuring impedance or related variables} · CPC title

• G01R31/2824

  testing of oscillators or resonators · CPC title

• G01R31/2829 Primary

  Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844) · CPC title

• G01R27/28

  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 title

• G01R23/02

  Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage · CPC title