radius2
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Hi Ken,
Thanks for the reply!
Here is the veriloga model for the switch. I have removed the terminals Vdd, gnd and oni which was some old stuff left behind.
module Switch(A, B, On); inout A; electrical A; inout B; electrical B; input On; electrical On;
parameter real R1 = 1; parameter real Roff = 100G;
parameter real vl_h = 1.2; parameter real vl_l = 0;
parameter integer trig_edge = 1; //+1 => rising edge, -1 => falling edge
real Rout;
analog begin @(initial_step) begin Rout = Roff; end
@(cross(V(On)-(vl_h-vl_l)/2, trig_edge)) begin Rout = R1; end
@(cross(V(On)-(vl_h-vl_l)/2, -trig_edge)) begin Rout = Roff; end I(A,B) <+ V(A,B) / Rout;
end
endmodule
I have also attached a picture of the clock signals. From there it can be observed that the clock phases are a quarter of clock period wide which will result in a floating capacitor during the time slot when all switches are open just as you observed. There are no parasitic capacitances in the switch.
The output log is listed below. At that time I had R1 = 1 and Roff = 10 G. The simulator continues indeed and the waveforms look alright but I don't know if the error messages are worrying.
*********************************************** Transient Analysis `tran': time = (0 s -> 2 us) *********************************************** Important parameter values: start = 0 s outputstart = 0 s stop = 2 us step = 2 ns maxstep = 20 ns ic = all skipdc = no reltol = 100e-06 abstol(I) = 1 pA abstol(V) = 1 uV temp = 27 C tnom = 27 C tempeffects = all errpreset = conservative method = gear2only lteratio = 10 relref = alllocal cmin = 0 F gmin = 1 pS
Zero diagonal found in Jacobian at `net076' and `net076'. Zero diagonal found in Jacobian at `net076' and `net076'. Zero diagonal found in Jacobian at `net076' and `net076'. Zero diagonal found in Jacobian at `net076' and `net076'.
Warning from spectre at time = 1 ns during transient analysis `tran'. WARNING (SPECTRE-16266): Error requirements were not satisfied because of convergence difficulties.
tran: time = 64.67 ns (3.23 %), step = 20 ns (1 %)
Warning from spectre at time = 125.5 ns during transient analysis `tran'. WARNING (SPECTRE-16191): Minimum time step used. Solution might be in error. Warning from spectre at time = 125.5 ns during transient analysis `tran'. WARNING (SPECTRE-16191): Minimum time step used. Solution might be in error.
tran: time = 167.1 ns (8.35 %), step = 20 ns (1 %) tran: time = 250 ns (12.5 %), step = 11.47 ns (574 m%)
Warning from spectre at time = 250.5 ns during transient analysis `tran'. WARNING (SPECTRE-16191): Minimum time step used. Solution might be in error. Warning from spectre at time = 250.5 ns during transient analysis `tran'. WARNING (SPECTRE-16191): Minimum time step used. Solution might be in error.
tran: time = 352.1 ns (17.6 %), step = 20 ns (1 %)
Warning from spectre at time = 375.5 ns during transient analysis `tran'. WARNING (SPECTRE-16191): Minimum time step used. Solution might be in error. Further occurrences of this warning will be suppressed.
tran: time = 457.1 ns (22.9 %), step = 20 ns (1 %) tran: time = 562.1 ns (28.1 %), step = 20 ns (1 %) tran: time = 667.1 ns (33.4 %), step = 20 ns (1 %) tran: time = 750 ns (37.5 %), step = 11.47 ns (574 m%) tran: time = 852.1 ns (42.6 %), step = 20 ns (1 %) tran: time = 957.1 ns (47.9 %), step = 20 ns (1 %) tran: time = 1.062 us (53.1 %), step = 20 ns (1 %) tran: time = 1.167 us (58.4 %), step = 20 ns (1 %) tran: time = 1.25 us (62.5 %), step = 11.47 ns (574 m%) tran: time = 1.352 us (67.6 %), step = 20 ns (1 %) tran: time = 1.457 us (72.9 %), step = 20 ns (1 %) tran: time = 1.562 us (78.1 %), step = 20 ns (1 %) tran: time = 1.667 us (83.4 %), step = 20 ns (1 %) tran: time = 1.75 us (87.5 %), step = 11.47 ns (574 m%) tran: time = 1.852 us (92.6 %), step = 20 ns (1 %) tran: time = 1.957 us (97.8 %), step = 20 ns (1 %) Number of accepted tran steps = 1954 Intrinsic tran analysis time = 310 ms. Total time required for tran analysis `tran' was 320 ms.
Warning from spectre. WARNING (SPECTRE-6006): 25 warnings suppressed
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