Diplexer

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Design Notes

RF Diplexer

This example illustrates the implementation of an RF diplexer in VSS. The diplexer is configured by defining two frequency ranges and their loss characteristics. The measured S21 is shown in the S21 graph; it uses system diagram "Diplexer" whose settings have been updated to generate frequencies from 0.8 to 3.2 GHz. The system diagram "Modulated Test Bench" generates four modulated signals at various frequencies, combines them and then passes the resulting signal through the diplexer. The Spectrum graph shows the frequency content at each diplexer output. User can monitor each of the signals at either diplexer output.

Some of the parameters of the modulated sources are linked to the corresponding ones in the first QAM_SRC block. This is done by using notation PARAM@BLOCK.IDVAL, where PARAM is the parameter name in the block BLOCK with ID set to IDVAL. If linking to parameters from the same block, notation PARAM@ can be used, instead. In this example, the RATE and SMPSYM parameters in the bottom three QAM_SRC blocks are linked to the corresponding parameters in the top one, allowing user to change them from a single location. This is a simple technique to avoid defining equations for specific parameters.

The project is configured to use a measurement noise floor during time-domain simulations to avoid cases where observed signals appear below the noise floor. This can be set under the RF Options tab in Options/Default System Options > Noise Options > TD Spectrum Noise Floor Use > Use measurement noise floor.

System Diagram - Diplexer

System Diagram - Modulated Test Bench

Graph - S21

Graph - Spectrum