Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
1997-04-21
2001-05-08
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C327S328000, C327S333000
Reexamination Certificate
active
06229296
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to electronic circuits and in particular the present invention relates to a circuit and method for measuring and forcing an internal voltage of an integrated circuit.
BACKGROUND OF THE INVENTION
Integrated circuits comprise a collection of transistors and other semiconductor devices interconnected on a semiconductor substrate. During production, an integrated circuit is encapsulated, for example, in a plastic body. Further, a passivation layer comprising silicon dioxide, for example, may be formed on the integrated circuit prior to encapsulation to protect the junctions and surfaces of the semiconductor devices of the integrated circuit from harmful environments. The integrated circuit interfaces with other components of a system via a number of metal pins that extend from the plastic body. The pins provide electrical connection to various internal points or nodes in the integrated circuit. Typically, many internal nodes in the circuit that can impact the performance of the integrated circuit are not connected to a pin.
For example, the substrate voltage is a measurable quantity that can affect the operation of an integrated circuit such as a refresh operation in a dynamic random access memory. However, the substrate voltage is not typically provided at a pin of the integrated circuit. If a problem is suspected with the substrate voltage once the integrated circuit is packaged or passivated, an engineer must remove at least a portion of the plastic casing or passivation layer or both and place a probe at the proper node to determine the voltage. Based on the measurement, process parameters may be adjusted for further production. However, this procedure is time consuming and subject to the accuracy of the set up of the testing equipment.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a circuit and method for measuring and forcing an internal voltage in an integrated circuit without having to remove either the plastic body or the passivation layer.
SUMMARY OF THE INVENTION
The above mentioned problems with measuring internal voltages in an integrated circuit and other problems are addressed by the present invention and which will be understood by reading and studying the following specification. A circuit is described which measures voltages at internal nodes of an integrated circuit without removing a plastic body or a passivation layer.
In particular, the present invention describes a circuit for reading a voltage at a node of an integrated circuit. The circuit comprises a pass circuit that has an input coupled to the node of the integrated circuit. The circuit provides a measurement of the voltage at the node as an output to a pin. A reset circuit is coupled to the pass circuit and is operable to activate and reset the pass circuit. Finally, a pass control circuit is coupled to provide an output signal to the pass circuit that drives the pass circuit when active to pass the voltage at the node to the pin. The circuit can also force the voltage at the node of the integrated circuit by applying a voltage to the pin.
In one embodiment, the present invention provides a bi-directional voltage pass circuit coupled between first and second nodes of an integrated circuit. The voltage pass circuit includes a pass element that is coupled to the first node of the integrated circuit. The voltage pass circuit further includes a reset circuit that is coupled to the pass element and is operable to activate and reset the pass element. The voltage pass circuit also includes a pass control circuit that is coupled between the second node and the pass element. The pass control circuit incudes. a scaler circuit that establishes a ratio between the voltages at the first and second nodes so as to selectively pass voltages between the first and second nodes.
In another embodiment, the present invention provides an integrated circuit that includes a plurality of semiconductor devices formed on a semiconductor substrate. The semiconductor devices are coupled together to perform a function, e.g., data storage as in a dynamic random access memory device. The integrated circuit has input and output pins and includes at least one internal node that has a measurable voltage. The integrated circuit further includes at least one circuit that is coupled to measure the voltage of the internal node. The at least one circuit includes a pass element coupled to a pin of the integrated circuit. Further, the at least one circuit includes a reset circuit coupled to the pass element that activates and resets the pass element. The at least one circuit further includes a pass control circuit that is coupled between the internal node of the integrated circuit and the pass element. The pass control circuit incudes a scaler circuit that establishes a ratio between the voltages at the pin and the internal node so as to selectively pass voltages between the internal node and the pin.
In another embodiment, a bi-directional voltage pass circuit is provided. The pass circuit comprises an internal node and an input/output pin. The pass circuit further includes a field effect transistor with first and second source/drain regions. The first source/drain region is coupled to the input/output pin. A voltage scaler circuit is coupled between the internal node and the second source/drain region of the field effect transistor. The voltage scaler circuit establishes a ratio between the voltage at the internal node and the input/output pin such that the field effect transistor can pass high voltage levels to and from the internal node.
REFERENCES:
patent: 4490673 (1984-12-01), Blum et al.
patent: 4504784 (1985-03-01), Goel et al.
patent: 4550289 (1985-10-01), Kabashima et al.
patent: 4839865 (1989-06-01), Sato et al.
patent: 4970454 (1990-11-01), Stambaugh et al.
patent: 4985672 (1991-01-01), Hashimoto et al.
patent: 5030904 (1991-07-01), Tanksalvala et al.
patent: 5107208 (1992-04-01), Lee
patent: 5157629 (1992-10-01), Sato et al.
patent: 5196787 (1993-03-01), Ovens et al.
patent: 5253255 (1993-10-01), Carbine
patent: 5488426 (1996-01-01), Pack
patent: 5498972 (1996-03-01), Haulin
patent: 5508631 (1996-04-01), Manku et al.
patent: 5526312 (1996-06-01), Eltoukhy
patent: 5581176 (1996-12-01), Lee
patent: 5627478 (1997-05-01), Habersetzer et al.
patent: 5642057 (1997-06-01), Oke et al.
patent: 5648730 (1997-07-01), Bhuva et al.
patent: 5657328 (1997-08-01), Swoboda et al.
patent: 5739868 (1998-04-01), Butler et al.
patent: 5751158 (1998-05-01), Loughmiller
patent: 5786703 (1998-07-01), Piirainen
patent: 5847552 (1998-12-01), Brown
Millman, J., et al., “Integrated Electronics: Analogs and Digital Circuits and Systems”,McGraw-Hill Book Company, Inc., 330-331, (1972) (Month unavailable).
Duesman Kevin G.
Loughmiller Daniel R.
Sher Joseph C.
Kobert Russell M.
Metjahic Safet
Micro)n Technology, Inc.
Schwegman Lundberg Woessner & Kluth P.A.
LandOfFree
Circuit and method for measuring and forcing an internal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit and method for measuring and forcing an internal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit and method for measuring and forcing an internal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520125