DE10055002A1 - Device for measuring voltage potentials and analogue electrical signals of an integrated circuit has a multiplexer connected to a large number of measurement points and connected to an analog-digital converter and memory - Google Patents

Abstract

Device for measuring voltage potentials and instantaneous values from analogue electrical signals at measurement points (1,2,3...n) of an integrated circuit (13) relative to a reference potential, particularly earth. Device comprises an analogue multiplexer (10), the inputs of which are from connectors to the measurement points and the output of which is connected to a circuit (11) for formation of a difference value between the input and the reference potential. The difference is digitized using an ADC (11) and stored in memory (12).

Description

The invention relates to a device for detecting Voltage potentials and instantaneous values of analog electrical signals at measuring points of an integrated Circuit relative to a reference potential, especially ground.

Such a device is used, for example Design analysis of components of an integrated circuit used. If the integrated circuit is unpacked So-called probes or probes, d. H. very thin tips made of conductive material mechanical manipulators placed on a wafer which the integrated circuit is implemented, and with connected to external measuring devices. In the case of packaged integrated circuits are u. a. similarly the Connections of the respective chip contacted. The structure such conventional devices are relative complicated and their use is complex. Further these devices are less suitable, the Voltage potentials and analog electrical signals during other investigations on the integrated circuit easy to record.

An object of the invention is a device of the type mentioned at the beginning, which create without great Effort in a reliable manner the voltage potential and Guaranteed signal acquisition.

This object is achieved by the features of claim 1. Advantageous developments of the invention are in the Subclaims specified.  

Instead of the previously used manual point-by-point potential and signal detection, the invention sees a simultaneous Measurement at all relevant measuring points using a Analog multiplexers before. At the output of this multiplexer the input signals are serial and are then individual compared with the desired reference potential. The corresponding difference or comparison result subject to an analog / digital conversion according to the invention and written to a buffer and from there every complete measuring cycle.

Determining the potential difference between the multiplexed test leads and the reference potential can be in in any defined order.

The device according to the invention allows by using the analog multiplexer the relevant voltages and Instantaneous values of the analog electrical signals also during other investigations on the integrated circuit capture, especially record.

Known analog / digital converters allow in the input stage a comparison between the applied analog signal and an external voltage reference, which is why the Differential formation circuit, the multiplexer downstream is integrated in the analog / digital converter is.

In order to take account of the conditions that occur in practice wear, the measurement is advantageously carried out by means of Device according to the invention with variable clock rate.

The output of the digital signals from the buffer is done either serially over a single one Output connection or in parallel over several such Connections.  

The invention is described below with reference to the drawings exemplified in more detail; the only figure in the drawing shows schematically in the form of a block diagram preferred embodiment of the device according to the invention.

Of the integrated circuit 13 to be tested, the measuring points 1, 2, 3,. , , n-1, n (n is an integer). These measuring points are connected to n connections of an analog multiplexer 10 via measuring lines. On the output side, the multiplexer 10 is connected to an analog / digital converter 11 , the output of which is connected to a buffer store 12 which comprises memory cells U ₁ to U _n . A reference potential in the form of an external voltage reference V _{REF is} applied to the input stage of the analog / digital converter 11 . This voltage _reference V _REF serves to form a difference between the voltage potential or instantaneous value of the analog electrical signal present at the output of the multiplexer 10 , which is then converted in the subsequent converter stage into a digital signal, which is stored in the buffer store 12 . As soon as the difference between all voltage potentials or instantaneous values of analog electrical signals at measuring points 1, 2, 3,. , , n-1, n are recorded and stored in digital form in the digital buffer store 12 , these values are either output serially or in parallel from the buffer store 12 and displayed or recorded on a device (not shown) suitable for this purpose.

The control of the analog / digital converter 11 takes place in a known manner via a clock input (clock) and an enable input (enable). This clock rate is also used to control the analog multiplexer 10 and the memory 12 and can preferably be changed if necessary.

Claims (5)

1. Device for detecting voltage potentials and instantaneous values of analog electrical signals at measuring points (1, 2, 3,..., N-1, n) of an integrated circuit 13 relative to a reference potential, especially ground, characterized by an analog multiplexer ( 10 ), the inputs of which can be connected to the measuring points (1, 2, 3,..., N-1, n) via measuring lines, and the output of which is connected to a circuit for forming a difference between the multiplexer output signal and the reference potential , an analog / digital converter ( 11 ) for extracting a digital signal from the analog difference signal of the difference-forming circuit, and a memory ( 12 ) for temporarily storing the digital signals. 2. Device according to claim 1, characterized in that the difference formation circuit in the analog / digital converter ( 11 ) is integrated, at which the reference potential is as an external voltage reference (V _REF ). 3. Device according to claim 1 or 2, characterized characterized that they have a variable clock rate is operable. 4. The device according to claim 1, 2 or 3, characterized by a parallel output of the digital signals from the buffer ( 12 ). 5. The device according to claim 1, 2 or 3, characterized by a serial output of the digital signals from the buffer ( 12 ).