Impedance matching is important for a multitude of disparate types of circuitry, and ensuring proper operation of impedance-matching circuitry can be important to ensure quality and long-term performance. For instance, NFC (near field communication) controller integrated circuits (ICs) often provide a mechanism to check that discrete components are operating properly. Such components may, for example, include impedance matching circuitry connected between a chip and a contactless antenna. It can be important to ensure that these components are properly soldered on a PCB (printed circuit board) or otherwise connected. Such approaches may be referred to as an antenna self-test, and can facilitate the production test of a device that embeds an NFC solution.
While such testing approaches are valuable, they can be challenging to implement. For instance, it can be useful to ensure that RF (radio frequency) front-end components such as a matching network and antenna, meet design specifications. Variations in circuit operation may cause a shift in signal communications (transmission and/or receiving) gain and resonant frequency in an antenna and matching network, which may in turn have a significant impact to signal communications performance. For example, degradation in receiver circuitry gain can degrade receiver sensitivity. In addition, issues with transmission gain can reduce output power from an NFC driver into a matching network and antenna system, which may in essence lower power radiated from the antenna. Probing circuitry in order to test for such aspects can be difficult to do with accuracy, and may require circuit design modifications and space for utilizing a probe.
These and other matters have presented challenges to impedance matching circuitry and its implementation, for a variety of applications.