Derivative superposition (DS), reduces distortion by using an auxiliary circuit to generate an outofphase replica of the IMD tones. In this talk, Carlos Saavedra discusses work he has carried out that uses DS to improve the output OIP3 of power amplifiers.

Intermodulation distortion (IMD) refers to the phenomenon where the spectral lines of an informationbearing signal interact with themselves to yield new, undesired, spectral lines as they pass through a circuit. While some of the spurious tones are easily eliminated through filtering, others are more difficult to deal with because they appear within the band of the information signal and interfere with it. The study of IMD has a rich history and multiple techniques have been developed over time to mitigate it. One such method is known as derivative superposition (DS), which reduces IMD distortion by using an auxiliary circuit to generate an outofphase replica of the IMD tones produced by the main circuit. First introduced in the late 1990s, DS has attracted much attention due to its small footprint and low power consumption. This talk will discuss work we have carried out at Queen's that uses DS and digital assist to improve the output thirdorder intercept point (OIP3) of galliumnitride (GaN) power amplifiers from by +40 dBm to +50 dBm over a 5 GHz span. A standalone distortion cancelling cell will also be presented which can improve the OIP3 of a generic offtheshelf microwave amplifier by 7.5 dB. The talk will conclude with a discussion of mixer linearization using DS and digital assist techniques.