Testing the PLC hardware implementation includes validating the coupling circuit and the band-pass filter in the receive path.

To check the coupling circuit, the impedance was measured using a frequency response analyzer (Venable Instruments Model 3120). Importantly, the coupling network needs to present a high impedance at the PLC carrier frequencies and maintains lower impedances outside the communication band. Figure 4-12 shows the measured impedance. Yellow markers highlight the impedance at the mark and space frequencies of the RSD PLC protocol.

Figure 4-12 Impedance Coupling Circuit

An additional band-pass filter is implemented in the receive path. In this path it is important that the pass band is set to the carrier frequencies of the PLC communication. Figure 4-13 shows the measured transfer curve of the bandpass filter. The pass band is located between 70kHz and 150kHz. The same frequency response analyzer was used for this measurement.

Figure 4-13 Transfer Curve Band-Pass Filter Receive Path

This design verified the PLC coupling circuit and AFE031 with rapid shutdown function in combination with the TIDA-060001 reference design. See also SunSpec Rapid Shutdown Transmit and Receive Reference Design.