RFIC dude,
It hard to know what is going wrong without seeing your netlist. The most common error involves incorrectly specifying the clock. You should identify the source or sources that make up the clock by giving them a
fundname and then giving the same name to the envelope following analysis using the
clockname parameter. The low frequency sources should either not have a
fundname or it should be a different one.
The following netlist works for me.
Code:// Test circuit for Envelope Following
simulator lang=spectre
Vlo lo 0 vsource type=sine freq=100MHz ampl=1 fundname="LO"
Rlo lo 0 resistor r=50
Vrf rf 0 vsource type=sine freq=100kHz ampl=1
Rrf rf 0 resistor r=50
envelope envlp start=1n stop=50us harmsvec=[1 3] clockname="LO"
-Ken