Waveform turbines and their function in IC testing

Introduction

Semiconductors are the important part fueling the expansion of industries similar to automotive, renewable power, communications, info expertise, protection, and client 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 parts and circuits on a standard semiconductor base. ICs rapidly changed vacuum tube-based digital tools 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 essential parts in quite a few merchandise and processes. ICs might be a number of discrete parts packaged collectively, similar to digital logic circuits, microcontrollers, microprocessors, digital reminiscence storage, analog circuits and amplifiers, radio frequency (RF) / microwave (MW) analog parts and circuits, and built-in energy circuits. This text focuses on utilizing waveform turbines to check varied varieties of ICs.

IC design and take a look at course of circulation

IC design and testing are advanced processes involving precision and experience to fulfill 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 based mostly 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 practical testing to make sure they perform accurately.

Determine 1 The IC design and take a look at course of circulation together with IC design and simulation, wafer processing, parametric testing, lead body/wire bonding, package deal testing, and ending with practical take a look at. Supply: Keysight

Wafer-level verification testing

Through the design or front-end IC manufacturing stage, the ICs are usually examined on the wafer stage. Testing ICs on the upstream wafer-level course of might be difficult, particularly when utilizing wafer-probing instruments. Nevertheless, it’s needed 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 practical verifications might be carried out similar to catastrophic shorting, leakage, energy provide, and basic enter / output situations. Supply: Keysight

On the wafer stage, you’ll be able to carry out checks for fundamental perform verifications similar to catastrophic shorting, leakage, energy provide, and basic enter / output situations. Sign sources can come from programmable DC energy provides, supply and measure models, and general-purpose waveform turbines.

Through the IC design stage, take a look at engineers can carry out noise, DC parametric, and S-parameter characterization work at wafer-level probing checks. This course of drastically reduces the time to the primary measurement and gives correct and repeatable gadget and part characterization.

Package deal testing

After the ICs are positioned on lead frames, wire-bonded to their respective leads and encapsulated, they’re of their ultimate bodily kind. Assessments are performed to make sure that the packaged ICs meet packaging expectations, similar to no quick circuits, open or weak connections, correct electrical isolation between inner circuits, and extra.

Waveform turbines present clear alerts and managed frequency and amplitude noise ranges for sign integrity and low-frequency noise checks. Determine 3 reveals how waveform turbines 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 turbines can present clear alerts and managed frequency and amplitude noise ranges. Supply: Keysight

Submit-packaging practical testing

Submit-packaging practical testing, often known as end-of-line testing, is usually advanced 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 prospects.

Waveform turbines generate advanced 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. Trendy waveform turbines are versatile in producing all types of alerts, similar to digital, analog, advanced modulated, low to excessive frequency, burst, synchronized, and arbitrary waveform alerts for all IC functions.

Most popular waveform generator traits

Waveform turbines 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, secure, and dependable sign. The sign generated shouldn’t range no matter frequency or pattern price. Moreover, sure waveform generator specs for IC testing are vital.

A clear and secure sign supply

A clear sign supply gives true and unadulterated alerts with out noise or interference from different overseas alerts. The alerts are measurable by the purity of a sign void of harmonic distortions and jitter. A clear and secure 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 features and performances. The extra errors launched from the sign supply, the extra degraded the product specification turns into as a result of measurement uncertainties.
To keep away from false take a look at outcomes: A secure 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 similar to false take a look at outcomes have an effect on downstream checks. Delivery the incorrectly characterised product to prospects is the worst-case situation.
Repeatable and dependable efficiency: Clear alerts will even present optimized repeatability take a look at situations 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 might be made extra dependable by changing a real-world sign with a sign created by a waveform generator.

Noise additive

Moreover having clear alerts to characterize the efficiency of IC gadgets, including noise to check alerts simulates real-world noisy transmission, crosstalk, and EMI. As a substitute of getting one of the best product efficiency specs, including noise stresses the IC below take a look at and determines the robustness of the merchandise.

Appropriate waveform turbines can produce variable noise bandwidth to manage the frequency content material of the take a look at sign. Determine 4 illustrates that this strategy allows managed stress testing of the ICs below 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. Functions that use mixed-signal ICs embody analog-to-digital converters, digital-to-analog converters, energy administration circuits, microcontroller circuits, and bodily parameter sensing measurements similar to temperature, humidity, and stress. Waveform turbines can simulate each digital and analog alerts to check mixed-signal ICs.

Arbitrary waveform alerts created by software program

Trendy waveform turbines can generate arbitrary waveforms to simulate actual IC take a look at functions. These turbines normally include software program functions that create arbitrary waveforms.

Importing simulated or actual alerts

Essentially the most direct technique 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 technique 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 wish to generate the waveforms immediately in MATLAB or Python programming and switch these waveforms to the waveform turbines. For instance, Determine 5 reveals how MATLAB understands the plotting of a fancy waveform. The waveform is a simulation of a bit of an electrocardiograph (ECG) coronary heart sign exhibiting a part of the PQRST factors. In actual fact, 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 gives choices to ship waveform factors as a binary block to an arbitrary waveform perform generator. The explanation for sending a waveform as binary information fairly 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 strategy allows constant and arranged testing for a lot of varieties of IC take a look at functions.

Creating waveforms in playlist take a look at sequences

Most trendy waveform turbines 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’ll be able to mix particular person arbitrary waveform segments into user-defined lists or sequences to kind longer, extra advanced waveforms.

The necessity for waveform turbines

Waveform turbines are versatile take a look at devices important all through IC design and manufacturing processes. They’ll generate all types of alerts, similar to digital, analog, advanced modulated, low to excessive frequency, burst, synchronized, and arbitrary waveform alerts, for a lot of varieties of IC functions.

Designers can benefit from the highly effective capabilities of waveform turbines to create clear and secure alerts in addition to to manage IC stress testing by including incremental noise content material to the take a look at alerts. Waveform turbines can even generate all types of arbitrary waveforms to simulate actual IC take a look at functions, that is essential as ICs are getting smaller and combine extra advanced features.

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 methods, digital multimeters, and training product options. Bernard acquired his Bachelor of Electrical Engineering from Southern Illinois College, Carbondale, Illinois.

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