Precision LVDT Signal Conditioning Using Direct RMS to DC Conversion

摘要

Figure 2 shows the amplitude and phase outputs ot the circuit in Figure 1. A novel approach to LVDT signal conditioning yields stable, precise performance and a low IC count. Unlike a synchronous demodulation scheme, the accuracy of the circuit does not hinge on a manual phase adjustment―only on the built-in high precision of the LTC1967 (or LTC1968) true RMS to DC converter. The circuit is robust enough for many industrial and instrumentation applications―it maintains good precision over temperature and it is immune to input signal phase. A separate, easily-calibrated phase detector determines which side of center the LVDT core occupies.