Revision(s) Affected:

IWR1642 ES1.0 and ES2.0

Description:

There is a finite isolation between the RF pins/package and the FMCW synthesizer. This can create spurious tones at the synthesizer output and lead to appearance of 2nd order harmonics and inter-modulations of expected IF frequencies at RX ADC output. The amplitude of the 2nd harmonic could be as high as -55 dBc , referenced to the power level of the intended tone at the LNA input.

Workaround(s):

No workaround available at this time. However, in many typical radar use-cases the HD2 does not affect the system performance due to two reasons:

1. Since the HD2 comes from a coupling to the LO signal, there is an inherent suppression of the HD2 level due to the self-mixing effect (that is, phase noise and phase spur suppression effect at the mixer).
2. In real-life scenarios there is often a double-bounce effect of the radar signal reflected from the target, which leads to a ghost object at twice the distance of the actual object. This effect is often indistinguishable from the effect of HD2 itself.