An IIP2 calibration technique for direct conversion receivers

Wideband cancellation of second order intermodulation distortions in a 60GHz zero-IF mixer

“…Single-parameter tuning methods can adjust V off to vary I imd2DIF [5]. They can also adjust output resistance mismatches (įR out ) or output capacitance mismatches (įC L ) to vary įz L [6]- [7]. To make the two terms in (6) cancel out each other by tuning only one parameter, the following should be satisfied:…”

“…However, choosing only one parameter to tune, can only satisfy (9) at one single frequency point, because for each frequency the tunable parameter has a different optimum. Even a two-dimensional tuning involving įR out and įC L is not sufficient [7], because it can only set (6) to zero at a single frequency point.…”

“…Therefore, any IMD2 cancelation mechanism applied to a 60GHz mixer must be functional across a wide frequency range. Narrowband IMD2 cancelation techniques, like conventional single-parameter and double-parameter tuning, are not beneficial since they suppress IMD2 at only one single frequency point [5]- [7].…”

A BiCMOS single ended multiband RF-amplifier and mixer with DC-offset and second order distortion suppression

“…The mixer DC-offset is not minimized after the trimming. In [15] an improvement for a previously published IP2 calibration method for a Gilbert cell type mixer is introduced. In the previous solution the IP2 was degraded as a function of the baseband frequency when a mixer with RC load was used.…”

“…The improved solution maintains a high IIP2 over the entire baseband frequencies in a WCDMA receiver by also trimming the mixer load capacitors. However, in order to implement the solutions in [14] and [15] an optimum trimming code has to be detected. For the code detection test tones have to be inserted into the receiver.…”