Abstract: CX is measured in the presence of RP by charging CX with a constant current IC for a period time and taking four (time, voltage) pairs: (tA,VA), (tB,VB), (tC,VC) and (tD,VD). The first pair are sufficiently close together that the short straight line segment connecting (tA, VA) and (tB, VB) is not significantly different from the corresponding segment of a true graph of the capacitor's actual charging. A similar requirement is imposed on the time interval between tC and tD. The time interval tAtB need not be the same as tCtD. The interval tBtC should be long enough that if there is significant RP present then there is at least a discernable difference between the true graph and a straight line between the first pair and the second. CX and RP are computed as a function of the four pairs and IC, and CX may then be diminished by a previously measured value for a stray capacitance present in the absence of CX.

Abstract: A delta-sigma converter has coarse and fine ADCs, wherein an integrated error signal is coupled to the coarse ADC whose output drives a DAC to create feedback that achieves loop balance. The coarse ADC provides the most significant bits of the result. The integrated error signal is also applied to a fine ADC whose output bits are not incorporated into the feedback, but which are combined with those of the coarse ADC and the combination applied to a filter that averages the hunting that represents loop balance. A DC feed forward circuit shunts the integrator with a replica of the applied input signal to apply it to the coarse ADC through a summer, allowing its output to be just the integrated error signal without including the applied input. If continuous integration is used, an AC feed forward circuit provides a compensatory voltage that is removed from the integrator output (or alternatively, is added to its input) and that corrects for a frequency dependent error.

Abstract: A housing for a thin active probe has two identical molded housing-halves that when assembled form a cavity that encloses the chassis upon which is carried the active circuitry of the probe. The parts exhibit complementary self-symmetry about a longitudinal axis, such that when one is rotated about that axis it performs the mating functions needed to interlock with another part representing its un-rotated self. Interlocking is accomplished by circular tabs and sockets that interfere and prevent the parts from separating once the tabs are in the sockets. The circular tabs are joined to the balance of the housing-half that carries them by a narrow neck and can be sprung over the other housing-half to return to their natural position and fit into a circular socket in that other housing-half.

Abstract: Uncontrolled characteristic impedance along a spring biased pin probe assembly is avoided by providing a stepped shelf of ground plane that extends outward along the pin and toward the target signal. The length of outward extension is chosen such that even when there is only (or at least) an expected minimum amount of compression of the spring while producing and maintaining contact, the entire exposed portion of the pin is over the shelf, whose depth of step has been selected to produce a selected Z0 for the exposed pin that matches Z0 for existing transmission lines already within the probe assembly. The spring biased pin may be a resistor tip spring pin that includes a small resistor in its tip.

Abstract: A solution to the problem of broken micro-browser probe assemblies caused by the accidental application of excessive force is to manufacture the rods out of a material that resists forces found in normal usage and appears stiff, but that will abruptly deform harmlessly under less force than causes permanent damage to other elements of the micro-browser. The sudden deformation serves as a signal to the operator to stop being a gorilla. That leaves the problem of re-shaping the rod. A preferred solution is to use as the rod a Nitinol superelastic metal wire that automatically returns to its previous shape once the force causing deformation is removed. An alternate solution is to make the rod from a length of Nitinol “memory metal” wire that restores itself to a pre-set shape upon the application of mild heat, such as immersion in a cup of hot water from an office coffee machine. The small circuit board and its components are not bothered by the bath.

Abstract: RF spectrum and FM characteristics of an SSC clock signal are measured with a high speed single-bit test channel that can be present in the Agilent 93000 SOC System. The SSC clock of interest is applied to one of the high-speed single-bit test channels. A conventional FFT is performed on the captured data to discover the aggregate nature of the distributed spectral components, which can then be compared with associated specifications. The captured data is applied to another algorithm to find the FM modulation profile. That algorithm involves operating on captured digital data to perform a frequency translation operation a first filtering operation, a discrete differentiation operation that includes raw phase extraction, followed by a second filtering operation. The algorithm for finding the SSC modulation profile does not require the high-speed digital channel to meet Nyquist sampling requirement.

Abstract: A cyclic reduced Gray code in n-many bits having 2k-many entries, for any natural number k, where 2(n?1)<2k<2n and n is a positive integer, is found by first constructing a 2n-many entry code in n-many bits with a reflected binary technique, and then selecting the last k-many ordered entries in the first half of the full reflected binary code, followed by the first k-many ordered entries in the second half of the full reflected binary code. These ordered 2k-many entries are a shortened cyclic reduced Gray code in n-many bits. Alternatively, the first k-many ordered entries in the first half of the full reflected binary code can be selected, followed by the last k-many ordered entries in the second half of the full reflected binary code.

Abstract: A digital oscilloscope assists in the process of identifying, cataloging and restoring views of interest within a stored trace acquisition by implementing the notion of bookmarks. In response to a command to establish a bookmark, the scope takes note of selected display control parameters, such as the location of the view in the overall acquired trace and horizontal time per division, and stores that as a named bookmark. The scope accepts from the operator a comment associated with each bookmark. Another command lists defined bookmarks and causes the scope to re-institute the view and parameters associated with a specified bookmark. There is a mechanism for editing the descriptors or parameters that are defined by a bookmark.

Abstract: A solution to the problem of broken micro-browser probe assemblies caused by the accidental application of excessive force is to manufacture the rods out of a material that resists forces found in normal usage and appears stiff, but that will abruptly deform harmlessly under less force than causes permanent damage to other elements of the micro-browser. The sudden deformation serves as a signal to the operator to stop being a gorilla. That leaves the problem of re-shaping the rod. A preferred solution is to use as the rod a Nitinol superelastic metal wire that automatically returns to its previous shape once the force causing deformation is removed. An alternate solution is to make the rod from a length of Nitinol “memory metal” wire that restores itself to a pre-set shape upon the application of mild heat, such as immersion in a cup of hot water from an office coffee machine. The small circuit board and its components are not bothered by the bath.

Abstract: Trial decimations are performed on an acquired waveform. Each trial produces a sequence of packets applied to a complexity detection circuit. Each packet contains a decimation value to be used in place of acquisition values to be suppressed along a decimation sample width. Each packet also includes the maximum and minimum values that occurred within the associated decimation sample. A plurality of counters record for a trial decimation the number of instances when the differences in waveform extremes exceed a corresponding plurality of selected thresholds. Complexity introduced by decimation will tend to produce waveforms having larger voltage excursions over the region of suppressed acquisition samples. The data in the counters is processed to produce a suite of histograms examined to select a decimation factor that does not introduce significant additional complexity.

Abstract: A probe pod housing is connected by a cable to an active probe. The probe pod housing carries a male push-on precision BNC connector that is also a cross-series adapter. The center conductor of the cable receives a male connector that then mates with the non-BNC end of the cross-series adapter. Auxiliary conductors that may also be carried by the cable are connected to male pins (soldered to a circuit board carried within the probe pod) with a push-on female in-line connector. The active probe itself uses a soldered-to-the-shield threaded nut technique. The nut threads into a metallic body that contains the impedance converter and that is enclosed by the body of the active probe. The cable is replaced by first unsoldering the center conductor (and also any auxiliary conductors). Then the nut (which is still soldered to the shield) is unscrewed from the metallic body, and the cable is free from the probe.

Abstract: A sampling transition-detector sets two latches to different values when an input signal comparator referenced to the selected voltage transitions during a sample interval: at the beginning one latch receives one comparison value while at the end the other latch receives an opposite comparison value. A difference (XOR) in latched values indicates a transition through the selected voltage during the sample interval. An additional latch is set by a second input signal comparator whose reference voltage is offset slightly from the selected voltage, It also clocked at the start of the sample interval. If the two latches clocked at the start of the sample interval are different, as indicated by another XOR, then the input was between the reference voltage and its offset counterpart. The OR of the two XORs is the desired indication.

Abstract: The push-on latching function of a male BNC latch carried in a housing, and the positive locking of fully mated male and female connectors, are performed by three parts: The first is a male double shell assembly having two male sleeves that receive an intervening BNC female shell. An outer portion near the middle of the male double shell carries several turns of an exterior left-hand thread. The second is a spring biased self-latching BNC latch having an interior bore by which it snugly engages, and then rotates upon, the exterior of the male double shell. One end of the BNC latch has ramps and detents for engaging the bayonet pins of a female BNC connector, and the other end has a section of exterior right-hand threads proximate the exterior left-hand threads of the male double shell. The third is a barrel that has a bore therethrough with both left and right hand internal threads that engage the exterior threads of the BNC latch and the male double shell.

Abstract: A low voltage source of input edges is AC coupled to positive and negative edge differentiators. Each differentiator briefly drives ON a corresponding normally OFF switch, the pair of which switches serves as an impulse driver and that may be clamped to symmetrical opposing reference voltages. The bi-stable switch driver responds to a particular polarity impulse driver voltage by applying thereto through a load resistor a percentage of a power supply voltage of opposite polarity. The impulse driver is also coupled to a complementary pair of MOSFET switches that are in series between precise reference voltages of opposing polarities, and whose common junction may be connected to a current determining resistance. The output of the MOSFET switches may be assisted by an auxiliary bi-stable output driver that reduces the amount of load current drawn from those MOSFETS.

Abstract: An eye diagram analyzer equips each SUT data and clock signal input channel with individually variable delays in their respective paths. For a range of signal delay of n-many SUT clock cycles, the SUT clock signal delay might be set at about n/2. For each data channel there is specified a point in time relative to an instance of the delayed clock signal (data signal delay) and a voltage threshold. The specified combination (data signal delay, threshold and which channel) is a location on an eye diagram, although the trace may or may not ever go through that location. A counter counts the number of SUT clock cycles used as instances of the reference for the eye diagram, and another counter counts the number of times the specified combination of conditions was met (“hits”).

Abstract: The various functions that are desirable for interior test memory within a memory tester are implemented in Memory Sets each serving as the host for one or sometimes more of such functions. For certain classes of testing a portion of interior test memory can be used as a Stimulus Log RAM that operates as an ideal DUT to create the correct conditions that are to exist in an actual DUT after testing. The actual part can then be tested, while the expected receive vectors are taken from the Stimulus Log RAM, and the comparison results sent to an ECR, Tag RAM's, etc., as usual. In this way the test program does not have to create or contain within itself the particular receive vectors that are the expected response from the applied stimulus.

Abstract: A trigger signal for a memory tester uses a (breakpoint) trigger qualified according to what part of the test program is being executed. The qualified breakpoint trigger can be delayed before becoming a system trigger signal that can be used to trigger a ‘scope mode and to force an error flag to a selected value so as to compel a particular path with the test program. To provide stable waveforms for the sweeping of the voltage thresholds and sample timing offset the memory tester records the addresses for a target sequence of transmit vectors issued during an initial pass through the test program subsequent to the occurrence of the trigger. These addresses are exchanged for the instructions themselves, which are then altered to remove branching, and stored in a reserved portion of the memory they came from. Once the altered target sequence is stored the desired information is produced by restarting the entire test program and letting it run exactly as before down to the trigger.

Abstract: One or more LIMMS devices on a substrate, possibly having same-surface signal conductors, are hermetically sealed by either: (a) Enclosing each entire LIMMS device beneath a common or respective outer cover that is separate from the LIMMS device(s) and impervious to contaminants; or (b) Fabricating each LIMMS device such that its individual cover block (which is already a component of the LIMMS and is not a separate outer cover) can be hermetically sealed against the substrate. Each case must limit the effects of the hermetic seal upon impedances. In case (a) the substrate is covered with a layer of dielectric material matching the ribbon-like footprint of the perimeter of the separate outer cover. In case (b), the entire (solid) footprint of the LIMMS cover block on the substrate receives a layer of dielectric material, which may itself then be covered, save for near its perimeter, with suitable adhesive. In case (a) the outer cover may be soldered to the perimeter footprint.

Abstract: Interpolation along an axis is performed on a Correlation Surface Array that was created from counting the instances of difference (XOR) between corresponding pixels of single bit resolution images having trial displacements. The interpolation is performed by finding the intersection of two straight line segments that are identified by the shape of the cross section of the Correlation Surface along the axis of interest. In the case of nine trial shifts there are three values in such a cross section, and they may seen as representing three points whose abscissas are the pixel shift amounts minus one, no shift, and plus one, and whose ordinates are the corresponding correlation values. In situations where navigation (and interpolation) is possible, these three points will have certain properties. The ususal case is that two of the points determine one line having a slope m, and the other point determines the other line (assumed to have slope −m).

Abstract: An eye diagram analyzer assigns a plurality of SUT data signals to be members of a labeled group of channels. There may be a plurality of such groups. In addition to mere superposition in an (X, Y) display space of the various i-many (X, Y)-valued pixels for individual component eye diagrams associated with that group, other measured data for those pixels within a group can be merged in various different modes to produce corresponding composite eye diagram presentations. E.g., in a Normalized Signal Density Mode the number of hits at each trial measurement point is summed over all channels in the group, and then divided by the total number of clock cycles measured for the ith measurement point in that group to produce a density Di associated with the corresponding ith pixel: (Xi, Yi, Di). If Di is rendered as a color or an intensity, the resulting eye diagram includes a representation (the Di) of a normalized density of transitions at each point (Xi, Yi), relative to that group as a whole.