RF Desense

Created; April/2020Last Updated: July/2023


Have you ever wondered why the connectivity of your electronic product can sometimes be unreliable or flaky, even when it's designed with a wireless module from a reputable vendor using the latest standards? While it might be tempting to blame the wireless module vendor for slow internet connections, the reality is more complex. The short answer is no; the wireless module vendor may not be the main culprit. Different products with the same wireless module part number can exhibit varying wireless performance. 

In this article, we will introduce the term "radio frequency (RF) desensitization," also known as "RF desense" in the industry. This will be the central focus of our discussion.


Before we delve deeper into the concept of RF desensitization, let's clarify some key terms used in this article:


The purpose of this article is to demystify, identify the root cause of, and mitigate RF desense problems. By the end of this article, an intelligent designer should be able to diagnose wireless issues, pinpoint the root cause, and apply appropriate desense mitigation techniques.


Receiver sensitivity refers to the minimum detectable receiving signal power of a digital radio receiver required to achieve a specific bit error rate (BER) in accordance with wireless communication standards like WiFi or Bluetooth.

Theory of Operation: 

A desensitized wireless receiver experiences an increased noise floor due to electromagnetic interference, resulting in a reduced received signal-to-noise ratio. This leads to degraded receiver performance in terms of throughput vs. range. To maintain the same receiver performance in the presence of RF interference, a higher receiving signal power is required. However, the transmit power from the access point or wireless router remains fixed. As a result, the effective communication link range between the access point and the radio receiver must be reduced, leading to a reduction in wireless range coverage.

The cause of desensitization is electromagnetic interference, which can originate from external sources (e.g., nearby electronics like TVs) or, more commonly, stronger self-generated interference within the electronic system of the product. Self-generated interference often causes poor wireless performance. A good analogy for desense is shooting oneself in the foot!

Detailed Analysis: 

Electromagnetic interference (EMI) always has a source and can couple to wireless receivers in various ways. In an embedded system, conducted coupling paths can be noise from the power supply for the RF receiver IC, while radiated paths can arise from unshielded DDR memory banks radiating electromagnetic energy during read or write operations. This interference is picked up by the radio receiver antenna, resulting in desensitization.

By examining each coupling path and identifying the sources of EMI, one can apply early mitigation measures to prevent poor wireless performance.

Root Cause Methods: 


One should create a Desense Matrix containing the following items to test the level of radio receiver desensitization. For example:


To understand the exact noise spectrum of a well-known noise source, such as a HDMI interface, one can perform PCB level simulations and analyze power spectral density (PSD) plots to evaluate how signal transmission affects victim radio operating bands.


Several mitigation techniques can be employed:

Example problem

RF Desense

This slide goes over a real problem that actually happened during a product development. A detailed root cause analysis is carried out; several mitigation changes are applied to the design, and lastly the changes are validated through a list of desense tests. 


In this article, we've learned that RF desense is a radiated/conducted immunity problem specifically for wireless receivers. Often these self-generated noise/interference can be greatly suppressed by following good placement, layout, filtering, and shielding guidelines. It's very easy to point finger to bad hardware as a cause of poor connectivity; as a good designer, we now know that it's not the RF IC that is the problem but rather the system around it. 

As an intelligent designer, we need to understand the system first to order to find root cause and can improve wireless performance and ensure reliable connectivity in electronic products.