FDC2214: Electrode waveform sanity check

Hello,

On FDC2214 datasheet figure 14, the sensor signal is drawn as a full sinusoidal waveform. This would be ideal for our application, as its spectral power should mostly be limited to the sensor frequency and its harmonics.

I developed a custom board with the FDC2214, using the same L and C values as the FDC2214 eval board. On my board, the waveform at IN0A with referenced to ground looks like this:

The waveform only has the positive phase of the sinusoid. The blue trace shows the FFT in range 0-5MHz.

Other users who posted the signal seem to show similar half-waves:

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/766139/fdc2214-overshoot-on-the-oscillation-signal-waveform

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/574959/fdc2214-connecting-a-capacior-to-ground-signal-unexpected-in-oscilloscope

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/536824/fdc2214-how-to-excite-lc-tank?tisearch=e2e-sitesearch&keymatch=FDC2214#

Is it possible to configure the LC Tank circuit to output a full sinusoidal waveform as shown in FDC2214 datasheet figure 14? 

Thanks,

-Josh