@Tim Edwards I modified the control voltages for the DPDT switch as well as added R46 and R47 , I now have a better picture of why the DPDT switch is not working well.

phase_shifter.sch

red and blue waveforms are for drain and source nodes of M9 respectively

orange and green waveforms are for drain and source nodes of M12 respectively

both M9 and M12 are pass transistors

@Stefan Schippers it seems that the DPDT switch is also working now. Please correct me if wrong.

phase_shifter.sch

I have not tested using

Vctrl4

yet

@Stefan Schippers I mean the cross-connection of the DPDT switch

for the DPDT switch, I am not sure in what situations (in terms of M2 and M3) should I turn on each of four different mosfets M1 ?

@Stefan Schippers I am finding a way to test all 4 connections (2 going through the pass transistors, the other 2 going through the cross-connections) separately (time-multiplexed) using only a single transient simulation with all the control voltages using only PULSE() spice syntax with varying frequencies or initial delay

Note: if I am connecting Pole 2 to Pole 3 for example, then I would want to ground Pole 1 and Pole 4.

I just noticed that there are only 3 different connections configurations. 1. P1 connects P3 , P2 connects P4 2. P1 connects P3 , P1 connects P4 3. P2 connects P3 , P2 connects P4 Please correct me if I miss anything.

The DPDT switch is also working for cross-connection which I forgot to include in previous message regarding different connections configurations

phase_shifter.sch

@Stefan Schippers the real issue comes now : which connection configuration does the phase shifter circuit actually use ?

image.png

@Stefan Schippers @Tim Edwards in the picture just above, the DPDT circuit block shows all 4 nodes are connected together which is just simply not realistic in reality. Please correct my understanding if wrong.

See http://meic.dongguk.edu/Van_viet.pdf#page=21