Theoretical Approach to Calculating Reverse Intermodulation Distortion in Voltage Mode Class D RF Power Amplifiers

The development of 5G technologies, Multiple-Input Multiple-Output (MIMO) systems and Internet of Things (IoT) leads to change in the traditional paradigm of frequency-territorial planning. Indeed, in addition to reducing the distance between base stations of cellular communication, there is a problem of come close to them by radio means of mobile devices. In these cases, reverse intermodulation distortion (RIMD) occurs between closely spaced simultaneously operating transmitters. If they fall into the reception band, they disrupt the normal functioning of radio equipment. Therefore, the requirements for transmitters EMC characteristics are increasing. Class D power amplifiers in addition to higher efficiency, potentially, may have lower RIMD. The article discusses RIMD in previously unexplored Voltage Mode Class D (VMCD) RF Power Amplifiers. The theoretical approach to calculating RIMD in VMCD RF power amplifiers has been developed. The analysis performed showed that in order to achieve the desired levels of intermodulation distortion, not exceeding -70 dB, it is necessary to ensure the difference in saturation resistances is not more than 20% and saturation time deviation from the meander is not more than 2 degrees.