Introduction
Semiconductors are the important element fueling the expansion of industries akin to automotive, renewable vitality, communications, info know-how, protection, and shopper electronics. The rise of their significance started within the late Nineteen Fifties when Jack Kirby and Robert Noyce invented built-in circuits (IC), which constructed digital elements and circuits on a standard semiconductor base. ICs rapidly changed vacuum tube-based digital gear as a result of they had been extra energy environment friendly, saved house, and extra dependable.
Over the previous six many years, ICs have superior considerably and are utilized in many industries as they’re crucial elements in quite a few merchandise and processes. ICs could be a number of discrete elements packaged collectively, akin to digital logic circuits, microcontrollers, microprocessors, digital reminiscence storage, analog circuits and amplifiers, radio frequency (RF) / microwave (MW) analog elements and circuits, and built-in energy circuits. This text focuses on utilizing waveform mills to check varied forms of ICs.
IC design and take a look at course of circulate
IC design and testing are complicated processes involving precision and experience to satisfy required specs. Engineers interact in iterations, optimizations, and validations to make sure the ultimate IC achieves the specified efficiency and reliability. In Determine 1, the method begins with software program modeling and simulation primarily based on IC specs. Subsequently, the design is etched onto a photomask and transferred to a silicon wafer throughout the wafer foundry stage. After wafer testing, the ICs are packaged and bear useful testing to make sure they operate appropriately.
Determine 1 The IC design and take a look at course of circulate together with IC design and simulation, wafer processing, parametric testing, lead body/wire bonding, bundle testing, and ending with useful take a look at. Supply: Keysight
Wafer-level verification testing
Throughout the design or front-end IC manufacturing stage, the ICs are typically examined on the wafer stage. Testing ICs on the upstream wafer-level course of could be difficult, particularly when utilizing wafer-probing instruments. Nevertheless, it’s crucial as a result of the packaging course of is expensive and complicated. Determine 2 reveals wafer probing and testing in progress.
Determine 2 Wafer-level IC probing and testing the place fundamental useful verifications could be carried out akin to catastrophic shorting, leakage, energy provide, and basic enter / output circumstances. Supply: Keysight
On the wafer stage, you possibly can carry out exams for fundamental operate verifications akin to catastrophic shorting, leakage, energy provide, and basic enter / output circumstances. Sign sources can come from programmable DC energy provides, supply and measure models, and general-purpose waveform mills.
Throughout the IC design stage, take a look at engineers can carry out noise, DC parametric, and S-parameter characterization work at wafer-level probing exams. This course of drastically reduces the time to the primary measurement and gives correct and repeatable gadget and element characterization.
Bundle testing
After the ICs are positioned on lead frames, wire-bonded to their respective leads and encapsulated, they’re of their ultimate bodily type. Exams are carried out to make sure that the packaged ICs meet packaging expectations, akin to no brief circuits, open or weak connections, correct electrical isolation between inside circuits, and extra.
Waveform mills present clear alerts and managed frequency and amplitude noise ranges for sign integrity and low-frequency noise exams. Determine 3 reveals how waveform mills can present managed simulated alerts into ICs for an oscilloscope to check sign integrity.
Determine 3 The attention diagram of an IC sign integrity take a look at the place waveform mills can present clear alerts and managed frequency and amplitude noise ranges. Supply: Keysight
Publish-packaging useful testing
Publish-packaging useful testing, also called end-of-line testing, is usually complicated and tedious. This course of is the final testing stage, throughout which the ICs are extensively examined to make sure they meet specified efficiency and high quality requirements earlier than they’re shipped to clients.
Waveform mills generate complicated variable patterns, real-world alerts, and even excessive use-case alerts to make sure that all ICs shipped meet the required efficiency specs and performance. Fashionable waveform mills are versatile in producing every kind of alerts, akin to digital, analog, complicated modulated, low to excessive frequency, burst, synchronized, and arbitrary waveform alerts for all IC functions.
Most popular waveform generator traits
Waveform mills in the marketplace have a variety of specs. Testing and characterizing ICs requires stringent specs. IC design engineers want a supply that produces a clear, low-distortion, steady, and dependable sign. The sign generated mustn’t range no matter frequency or pattern fee. Moreover, sure waveform generator specs for IC testing are vital.
A clear and steady sign supply
A clear sign supply gives true and unadulterated alerts with out noise or interference from different international alerts. The alerts are measurable by the purity of a sign void of harmonic distortions and jitter. A clear and steady sign is critical when testing ICs as a result of engineers need:
- One of the best product specification: ICs require exact and correct alerts to characterize and validate their capabilities and performances. The extra errors launched from the sign supply, the extra degraded the product specification turns into on account of measurement uncertainties.
- To keep away from false take a look at outcomes: A steady sign supply creates a constant take a look at course of. Consequently, the take a look at outcomes can precisely characterize the habits of the ICs. If the sign supply is unstable, issues akin to false take a look at outcomes have an effect on downstream exams. Transport the incorrectly characterised product to clients is the worst-case situation.
- Repeatable and dependable efficiency: Clear alerts may even present optimized repeatability take a look at circumstances to gauge the true efficiency of ICs. They won’t have undesirable harmonics and noise, rendering take a look at outcomes inaccurate. Moreover, a take a look at could be made extra dependable by changing a real-world sign with a sign created by a waveform generator.
Noise additive
Apart from having clear alerts to characterize the efficiency of IC gadgets, including noise to check alerts simulates real-world noisy transmission, crosstalk, and EMI. As an alternative of getting the very best product efficiency specs, including noise stresses the IC beneath take a look at and determines the robustness of the merchandise.
Appropriate waveform mills can produce variable noise bandwidth to regulate the frequency content material of the take a look at sign. Determine 4 illustrates that this method allows managed stress testing of the ICs beneath take a look at.
Determine 4 Including managed noise right into a take a look at sign (prime picture) leads to a loud ECG sign (backside picture). Supply: Keysight
Blended alerts
Many functions require mixed-signal ICs, that are primarily ICs with digital and analog circuits built-in and packaged collectively. Purposes that use mixed-signal ICs embody analog-to-digital converters, digital-to-analog converters, energy administration circuits, microcontroller circuits, and bodily parameter sensing measurements akin to temperature, humidity, and stress. Waveform mills can simulate each digital and analog alerts to check mixed-signal ICs.
Arbitrary waveform alerts created by software program
Fashionable waveform mills can generate arbitrary waveforms to simulate actual IC take a look at functions. These mills often include software program functions that create arbitrary waveforms.
Importing simulated or actual alerts
Essentially the most direct methodology for importing alerts is digitizing a real-world take a look at sign utilizing an oscilloscope, saving it in a format that’s readable along with your software program utility, digitally manipulating or conditioning the take a look at sign, after which transferring it to a waveform generator to regenerate the sign.
One other widespread methodology is to make use of waveform builder software program to generate customized arbitrary waveforms and mixing them into the specified simulated take a look at sign. Some IC design engineers might need to generate the waveforms instantly in MATLAB or Python programming and switch these waveforms to the waveform mills. For instance, Determine 5 reveals how MATLAB understands the plotting of a fancy waveform. The waveform is a simulation of a piece of an electrocardiograph (ECG) coronary heart sign displaying a part of the PQRST factors. The truth is, this waveform reveals solely the RST factors for the aim of making a T-wave rejection take a look at waveform. MATLAB can mannequin waveforms utilizing math equations and translate all these factors into a fancy ECG take a look at sign.
Determine 5 Utilizing math equations, assembling right into a simulated cardio ECG take a look at sign in MATLAB. Supply: Keysight
Determine 6 reveals the output of a cardio ECG take a look at sign generated from MATLAB. The MATLAB software program utility presents choices to ship waveform factors as a binary block to an arbitrary waveform operate generator. The explanation for sending a waveform as binary information relatively than ASCII information is easy—the binary information is way smaller than the equal ASCII information.
Determine 6 MATLAB can switch the above-simulated cardio ECG take a look at sign right into a waveform generator. Supply: Keysight
These strategies allow engineers to create the specified take a look at alerts for cataloging and storing in digital waveform libraries. This method allows constant and arranged testing for a lot of forms of IC take a look at functions.
Creating waveforms in playlist take a look at sequences
Most fashionable waveform mills can play varied segments of waveforms in sequence. Design engineers can construct a playlist of take a look at sequences with waveforms of incremental adjustments or good or unhealthy alerts to check the IC responses. Relying in your waveform generator’s capabilities, you possibly can mix particular person arbitrary waveform segments into user-defined lists or sequences to type longer, extra complicated waveforms.
The necessity for waveform mills
Waveform mills are versatile take a look at devices important all through IC design and manufacturing processes. They will generate every kind of alerts, akin to digital, analog, complicated modulated, low to excessive frequency, burst, synchronized, and arbitrary waveform alerts, for a lot of forms of IC functions.
Designers can reap the benefits of the highly effective capabilities of waveform mills to create clear and steady alerts in addition to to regulate IC stress testing by including incremental noise content material to the take a look at alerts. Waveform mills may also generate every kind of arbitrary waveforms to simulate actual IC take a look at functions, that is crucial as ICs are getting smaller and combine extra complicated capabilities.
Bernard Ang has been with Keysight Applied sciences (beforehand Hewlett Packard and Agilent Applied sciences) for greater than 30 years. Bernard held roles in manufacturing take a look at engineering, product engineering, product line administration, product improvement administration, product help administration, and product advertising and marketing. He’s at present a product marketer specializing in information acquisition programs, digital multimeters, and training product options. Bernard acquired his Bachelor of Electrical Engineering from Southern Illinois College, Carbondale, Illinois.
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