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Design >> RF Design >> Envelope Following Simulation of switched-cap TX
https://designers-guide.org/forum/YaBB.pl?num=1573844142

Message started by RFn00b on Nov 15^th, 2019, 10:55am

Title: Envelope Following Simulation of switched-cap TX
Post by RFn00b on Nov 15^th, 2019, 10:55am

Hi,

I'm designing a wireless transmitter that consists of a DAC, a switched-cap baseband filter and a passive upconverter. I'm trying to simulate the spectral performance (ACLR and EVM) and produce constellation plots using QAM signals. The signals have been generated in MATLAB with RRC pulse shaping or come straight from the Rectangular QAM16 modulator block in rfLib with the RRC implemented in VerilogA.

Using a transient simply takes too long as the system has 3 distinct clock domains: the sampling rate of the digital signal, fdata, the clock of the switched cap filter, fs, and the frequency of the local oscillator driving the upconverter, LO. I was told that envelope following analysis was the way to go, but I don't know how to set it up in my case.

I have read all relevant workshops provided within SpectreRF but they only cover the simple case where you have 1 LO and the baseband frequency. How can I configure the simulator now that I basically have two large tones at fs and LO? (please note that both fs and LO are square-wave signals with 25% duty cycle)

Thank you in advance!