Built-in self-test method and apparatus for single-pin crystal oscillators
A built-in self-test (BIST) methodology and apparatus provide for testing and calibration of an integrated circuit oscillator circuit topology that uses a one-pin (a single-pin) external resonator. The method employs dedicated test circuitry, also referred to herein as BIST apparatus, for the pass/fail verification of both the active and passive building blocks of the oscillator. At the same time, the methodology ensures accurate calibration and matching of the capacitors using dedicated digital circuitry and algorithms.
1. A built-in self-test (BIST) apparatus of an integrated circuit, comprising:
a reconfigurable capacitor connection matrix coupled to one or more of a plurality of programmable oscillator capacitors of an oscillator of the integrated circuit and an oscillator core of the oscillator;
a reconfigurable test matrix of the integrated circuit coupled to the oscillator core of the oscillator and a test element of the integrated circuit coupled to the reconfigurable test matrix, where the bias voltages of the oscillator core are evaluated by the test element in accordance with the reconfigurable test matrix; and
a control element coupled to and operable to control the reconfigurable capacitor connection matrix and the reconfigurable test matrix, the control element further operable to control one or more of the plurality of programmable oscillator capacitors to inhibit oscillation of a resonator of the oscillator before the bias voltages of the oscillator core are evaluated by the test element in accordance with the reconfigurable test matrix.
2. The apparatus of claim 1 , where the reconfigurable test matrix is a reconfigurable direct current (DC) test matrix and the test element is a DC test element and where the DC bias voltages of the oscillator core are evaluated by the DC test element in accordance with the reconfigurable DC test matrix.
3. The apparatus of claim 1 , where the reconfigurable capacitor connection matrix comprises a plurality of switching elements coupled to the plurality of programmable oscillator capacitors and where the control element controls the plurality of switching elements to selectively control the one or more programmable oscillator capacitors to inhibit oscillation of the resonator of the oscillator.
4. The apparatus of claim 1 , where the control element sets the one or more programmable oscillator capacitors to maximum values.
5. The apparatus of claim 4 , where the reconfigurable capacitor connection matrix comprises a plurality of switching elements that under control by the control element selects the one or more programmable oscillator capacitors.
6. The apparatus of claim 4 , further where the control element sets one or more of a second plurality of programmable oscillator capacitors of a second oscillator of the integrated circuit to maximum values.
7. The apparatus of claim 6 , where the reconfigurable capacitor connection matrix includes a plurality of switching elements and the control element controls the plurality of switching elements of the reconfigurable capacitor connection matrix to select the one or more programmable oscillator capacitors of the second plurality of programmable oscillator capacitors.
8. The apparatus of claim 1 , where the oscillator is a van den Homberg oscillator that comprises a single-pin resonator.
9. The apparatus of claim 1 , where the control element is a digital control element.
10. A built-in self-test (BIST) method for testing an integrated circuit oscillator circuit topology, comprising:
inhibiting oscillation of a resonator of an oscillator of the integrated circuit;
evaluating bias voltages of the oscillator core of the oscillator of the integrated circuit in accordance with a reconfigurable test matrix of the integrated circuit after the inhibiting the oscillation of the resonator of the oscillator.
11. The method of claim 10 , where a test element of the integrated circuit coupled to the reconfigurable test matrix evaluates the bias voltages of the oscillator core in accordance with the reconfigurable test matrix.
12. The method of claim 10 , selectively controlling one or more programmable oscillator capacitors of the oscillator of the integrated circuit to inhibit oscillation of the resonator.
13. The method of claim 12 , where selectively controlling the one or more programmable oscillator capacitors further comprises selectively controlling a plurality of switching elements of a reconfigurable capacitor connection matrix coupled to the oscillator core of the oscillator.
14. The method of claim 12 , further comprising setting one or more of the plurality of programmable oscillator capacitors to maximum values to inhibit oscillation of the resonator of the oscillator before evaluating bias voltages of the oscillator core.
15. The method of claim 14 , further comprising during a DC test:
setting the one or more of the plurality of programmable oscillator capacitors to maximum values by a control element; and
evaluating bias voltages of the oscillator core by a test element in accordance with a reconfigurable test matrix coupled to the oscillator core of the oscillator.
16. The method of claim 15 , further comprising selecting by a reconfigurable capacitor connection matrix under control of the control element the one or more of the plurality of programmable oscillator capacitors to be set to maximum values.
17. The method of claim 12 , further comprising selecting the one or more of the plurality of programmable oscillator capacitors to be set to maximum values.
18. The method of claim 12 , further comprising setting one or more a second plurality of programmable oscillator capacitors of a second oscillator of the integrated circuit to maximum values to further inhibit oscillation of the resonator of the oscillator before evaluating bias voltages of the oscillator core of the oscillator.
19. The method of claim 18 , further comprising selecting the one or more of the second plurality of programmable oscillator capacitors to be set to maximum values.