If electronics designers, engineers, and manufacturers are to be successful in bringing their products to market in good time, they will need to take certain critical steps to ensure electromagnetic compatibility (EMC).
After all, this isn’t just a “good to do” level of priority. Stringent regulations exist in this area, such as the UK’s Electromagnetic Compatibility Regulations 2016 – which are, in turn, derived from the European Union (EU)’s EMC Directive.
In the event, then, of electromagnetic interference (EMI) not being adequately addressed from an early stage of the design process, this can lead to non-compliance, and the need for expensive redesigns and delays.
The Role of Pre-Compliance Testing in Banishing High-Frequency Noise
This brings us onto the importance of pre-compliance testing for electronics products, including the evaluation of a given product’s EMI performance before formal certification. When this process is handled well, it can greatly help to minimise the aforementioned risks.
Across major markets such as the UK and Europe, it is essential for electronic devices to comply with the relevant EMC regulations. The rules set out in such legislation ensure that devices don’t emit excessive EMI and are not overly susceptible to external noise.
Given that there can be various adverse consequences if an electronic product fails compliance testing – such as penalties, product recalls, or the device even being banned from sale – it should be no surprise that firms invest greatly in pre-compliancetesting.
Engineers use pre-compliance testing as a means of pinpointing and addressing EMI issues during the design phase, long before they submit the given product for formal testing at an accredited laboratory.
Among the many EMI issues that can occur, high-frequency noise – sometimes referred to in the industry as “junk” – is a frequent culprit.
If steps aren’t taken to minimise this noise at an early stage, it could radiate or conduct through a given device, resulting in the product failing radiated or conducted emissions tests.
How Can First-Order RC Filters Contribute to Taming High-Frequency Junk?
A first-order RC filter is the simplest RC (resistor-capacitor) circuit; it consists of a single resistor and a single capacitor. Despite its simplicity (and actually because of it, as we will elaborate on later), it can be a highly effective tool for suppressing high-frequency noise.
The principle of how a first-order RC filter works is easy enough to understand: it filters electrical signals by allowing certain frequencies to pass, while attenuating (blocking) others.
There are two main types of first-order RC filter: low-pass filters and high-pass filters. As the respective names indicate:
- Low-pass filters allow low-frequency signals to pass while attenuating high-frequency components
- When a high-pass filter is used, signals with lower frequencies are reduced, and frequencies above a certain cutoff frequency are permitted to pass through.
So, if it is high-frequency noise that you are interested in blocking, a low-pass filter could be a straightforward and impactful remedy. For example, in an audio circuit, an RC filter can ensure clean signal transmission by eliminating unwanted high-frequency interference.
We mentioned the simplicity of a first-order RC filter above; indeed, this can be one of its greatest strengths. Given that such a filter only comprises two components, it can be easy to implement into designs where space is at a premium, as can be a frequent issue in modern electronics products such as wearables and Internet of Things (IoT) devices.
3 Tips for Designers Seeking to Make Pre-Compliance Testing Easier
Following these strategies will help to ensure the pre-compliance process for your electronics product(s) is as smooth as possible:
- Start Early
The incorporation of EMI mitigation – including RC filters – from the initial schematic design will greatly help reduce the need for costly reworking later.
- Use An RC Filter Calculator
It can be a time-consuming and error-prone process to manually calculate the resistor and capacitor values for RC filters. A reputable first-order RC filter design tool can greatly help to simplify this process by automating calculations and providing instant feedback.
- Invest In Real-World Test Equipment
It is possible to obtain affordable pre-compliance test setups, such as spectrum analysers or near-field probes, that are effective in measuring noise and validating filter performance.
Pre-Compliance Testing Can Greatly Help to Drive Down Unwanted High-Frequency ‘Junk’
The EMC regulations – not just in the UK, but also around the globe – can certainly be complex to navigate. However, it is also true that they play an imperative role for electronics designers, manufacturers, and consumers alike.
Tools such as RC filters, and the associated calculators that can be easily found online, can greatly help engineers to avoid nasty surprises during formal testing. As a result, firms can be well-placed to ensure compliance and get their product to market so much sooner.