A Technical Foundation for RF CMOS Power Amplifiers Part 4: Misunderstandings in PA design Earl McCune T his fourth part of the article series "A Technical Foundation for RF CMOS Power Amplifiers" [1] presents five misunderstandings regarding wireless signals and amplifier design that persist in the literature and generally cause confusion, particularly for engineers new to this art. Each of these misunderstandings is addressed for its realistic answer along with additional discussion about why addressing that misunderstanding matters. At the end, four fundamental technical foundations are identified that can reliably be used to check and validate ideas and approaches during design and development projects. A SerieS on CMoS TrAnSMiTTer TeChniqueS This article is the fourth in a series based on a presentation for the Advanced RF CMOS Transmitter Techniques Forum at the 2015 International Solid-State Circuits Conference in San Francisco. This presentation provided a technical background upon which all the other forum presentations expanded greatly. Converting the forum presentation into articles for IEEE Solid-State Circuits Magazine is being done in six parts: * Part 1: Key Power Amplifier Issues (Summer 2015 issue) * Part 2: Power Amplifier Architectures (Fall 2015 issue) * Part 3: Power Amplifiers Operated as Three Ports (Winter 2016 issue) * Part 4: Misunderstandings in PA Design (Spring 2016 issue) * Part 5: Making a Switch-Based Power Amplifier * Part 6: Relating Envelope Tracking and Polar Transmitters. Parts 5 and 6 will be published in consecutive issues of the magazine following this one. Digital Object Identifier 10.1109/MSSC.2016.2543062 Date of publication: 21 June 2016 1943-0582/16©2016IEEE IEEE SOLID-STATE CIRCUITS MAGAZINE S P R I N G 2 0 16 75