Automatic test equipment for testing an oscillating crystal and method for operating the same

Patent metadata

Field	Value
Publication number	US-9523733-B2
Application number	US-201414526065-A
Country	US
Kind code	B2
Filing date	Oct 28, 2014
Priority date	Nov 5, 2010
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

Embodiments of the invention relate to automatic test equipment for testing a circuit having an oscillating crystal and to a method for operating such automatic test equipment. A generator generates a first signal comprising an oscillating part having at least one predetermined frequency. A first terminal couples the first signal to the oscillating crystal. At least one predetermined frequency is located inside a predetermined window around one of the resonance frequencies of the oscillating crystal. An analyzer has a second terminal coupled to the oscillating crystal for detecting a second signal and a rectifier connected in series with a low-pass filter for rectifying and filtering the second signal. A detector for detects a DC-signal at the output of the low-pass filter and for signals a valid test result for the oscillating crystal if the DC-signal exceeds a certain threshold value.

First claim

What is claimed is:

1. Automatic test equipment for testing a circuit having an oscillating crystal, the automatic test equipment comprising:
a generator for generating a first signal comprising an oscillating part having a plurality of predetermined frequencies and a plurality of resonance frequencies;
a first terminal for coupling the first signal to the oscillating crystal, wherein the plurality of predetermined frequencies are located inside a predetermined window around one of the plurality of resonance frequencies of the oscillating crystal;
an analyzer, comprising:
a second terminal that is coupled to the oscillating crystal for detecting a second signal; and
a rectifier that is coupled in series with a low-pass filter for rectifying and filtering the second signal; land

a detector for detecting a DC-signal at the output of the low-pass filter and for signaling a valid test result for the oscillating crystal if the DC-signal exceeds a certain threshold value.

2. Automatic test equipment according to claim 1 , wherein the low-pass filter is a half-wave rectifier comprising a diode working as a rectifier and a wherein the filter comprises a capacitor working as a low-pass filter.

3. Automatic test equipment according to claim 1 , wherein the width of the window is a full width at half maximum of a resonance curve of the oscillating crystal at one of the resonance frequencies.

4. Automatic test equipment according to claim 1 , wherein the predetermined frequency equals one of the resonance frequencies of the oscillating crystal.

5. Automatic test equipment according to claim 1 , wherein the first signal comprises a plurality of predetermined frequencies corresponding to resonance frequencies of the oscillating crystal.

6. Automatic test equipment according to claim 1 , wherein the oscillating crystal is coupled to the automatic test equipment using switches having a low capacitive load.

7. A method of operating an automatic test equipment for testing a circuit having an oscillating crystal with a plurality of resonance frequencies, the automatic test equipment comprising: a generator, a first, and a second terminal, a detector, and an analyzer, the method comprising:
coupling the first and second terminal to different terminals of the oscillating crystal;
coupling a first signal that is generated by the generator via the first terminal to the oscillating crystal, wherein the first signal comprises an oscillating part having a plurality of predetermined frequencies that are located inside a predetermined window around one of the resonance frequencies of the oscillating crystal, wherein a width of the window is a full width at half maximum of a resonance curve of the oscillating crystal at one of the resonance frequencies;
detecting a second signal at the second terminal;
rectifying and low-pass filtering the second signal with the analyzer; and
detecting a DC-signal with the detector in the rectified and low-pass filtered signal and signaling a valid test result for the oscillating crystal if the DC-signal exceeds a certain threshold value.

8. The method according to claim 7 , wherein filtering the second signal uses a half-wave rectifier comprising a diode working as a rectifier.

9. The method according to claim 8 , further comprising using a capacitor as a low-pass filter.

10. The method according to claim 7 , wherein the width of the window is a full width at half maximum of a resonance curve of the oscillating crystal at one of the resonance frequencies.

11. The method according to claim 7 , wherein the predetermined frequency equals one of the resonance frequencies of the oscillating crystal.

12. The method according to claim 7 , wherein the first signal comprises a plurality of predetermined frequencies corresponding to resonance frequencies of the oscillating crystal.

13. The method according to claim 7 , wherein the oscillating crystal is coupled to the automatic test equipment using switches having a low capacitive load.

Assignees

• Texas Instruments Deutschland
• Texas Instruments Inc

Inventors

• Sonnhueter Ralf
• Ecker Anton

Classifications

• G01R31/2824 Primary

  testing of oscillators or resonators · CPC title

• G01R31/2841

  Signal generators · CPC title