open-source-silicon.dev

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<@U01819B63HP> I have added the necessary large shunt resistors to solve the singular matrix issue.

Now, I am trying to debug the DPDT switch.  It seems to be working (See `Vsw3` and `Vsw4` ) , with the exception of the *first 4 waveforms (red, blue, orange, green)*

<@U016EM8L91B> 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

<@U01819B63HP> it seems that the DPDT switch is also working now.  Please correct me if wrong.

2.png

<@U01F36ZPD3Q> for the RF details i am not the right one to ask to, I have one concern about the 1 ohm resistors shunting Vd9 and Vd12 to VCC_2: these are blocking all frequencies. Are you sure this is ok?

the 1 ohm resistor is only there for testing, it will be removed later

I have only tested direct connection between drain and source of the pass transistor

<@U01819B63HP> 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 ?

<@U01819B63HP> 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 <http://ltwiki.org/LTspiceHelp/LTspiceHelp/V_Voltage_Source.htm|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

<@U01819B63HP> the real issue comes now :   which connection configuration does the phase shifter circuit actually use ?

<@U01819B63HP> <@U016EM8L91B> 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>