Pushing Low Quiescent Power Op Amps to Greater than 55dBM 2-Tone Intercept
It is commonly expected that very low distortion amplifiers must dissipate considerable quiescent power to achieve their high linearity. With the advent of intrinsically low distortion current feedback op amps, along with the linearity improvements achieved by the negative feedback used in these devices, wideband low distortion amplifiers have become available at much lower quiescent power levels. This discussion will focus on the 2-tone, 3rd order intermodulation distortion of current feedback amplifiers. Following a brief review the harmonic distortion mechanisms of current feedback op amps, a simple means to further improve an already high intercept will be described. Having pushed the 3rd order spurious levels into the noise, an automated means of measuring these very low distortion levels will be described.