Method and apparatus for evaluating the effects of stress on an RF oscillator
AssigneeTexas Instruments Incorporated
InventorsAndrew Marsall, Srikanth Krishnan
Life of this patent
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Abstract
Apparatus and methods are disclosed for evaluating degradation of a transistor in a cross coupled pair of an RF oscillator independently. A MOS device can be coupled between a separated center-tap inductor. By appropriately sizing the MOS device and turning the MOS device on during operation of RF oscillator, a good contact can again be made that allows the oscillator to operate at design performance. By turning the MOS device off, the supplies can be separates such that I-V characteristics of both transistors of the cross-coupled pair may be obtained.
Claims12
A method to evaluate optimum power transistor switching characteristics for determining reliability limitations in an RF oscillator circuit, the method comprising:
- providing a cross-coupled transistor circuit comprising a first transistor and a second transistor, and coupled to a resonant tank, wherein the resonant tank comprises a center-tap inductor and at least one capacitor;
- splitting the center-tap inductor into a plurality of inductors comprising a first inductor with a first output and a second inductor with a second output;
- coupling a third transistor to the first output and to the second output located between the first inductor and the second inductor;
- turning the third transistor off;
- and
- testing at least one DC characteristic of the first transistor and testing at least one DC characteristic of the second transistor.
A circuit to allow analysis of stress characteristics in RF circuitry for determining reliability variation as a function of voltage, comprising:
- a first transistor and a second transistor coupled in a cross-coupled configuration, wherein a first gate terminal of the first transistor is coupled to a second drain terminal of the second transistor, and a second gate terminal of the second transistor is coupled to a first drain terminal of the first transistor;
- a resonant tank comprising a center-tap inductor comprising a plurality of inductors comprising a first inductor comprising a first output and a second inductor comprising a second output, at least one capacitor, and a third transistor;
- wherein the third transistor is coupled to the first inductor and to the second inductor;
- and
- further comprising a measurement device coupled to the first output of the first inductor or the second output of the second inductor, and configured to measure a degradation characteristic of the first transistor independent of the second transistor, and to measure a degradation of the second transistor independent of the first transistor.
A circuit to allow analysis of stress characteristics in RF circuitry for determining reliability variation as a function of voltage, comprising:
- a first transistor and a second transistor coupled in a cross-coupled configuration, wherein a first gate terminal of the first transistor is coupled to a second drain terminal of the second transistor, and a second gate terminal of the second transistor is coupled to a first drain terminal of the first transistor;
- a center-tap inductor comprising a plurality of inductors comprising a first inductor comprising a first output and a second inductor comprising a second output;
- a capacitor;
- and
- a third transistor;
- wherein the third transistor is coupled to the first inductor and to the second inductor;
- and
- further comprising a measurement device coupled to the first output of the first inductor or the second output of the second inductor, and configured to measure a degradation characteristic of the first transistor independent of the second transistor, and to measure a degradation of the second transistor independent of the first transistor.
Dependencies are inferred from the claim text.