Why you use transient simulation than DFT ?? Is PSS+THD simulation combination not suitable ??
Differential circuit is not an issue.You can use ideal balun,ideal transformer etc. to manipulate the simulation environment.You don't have to use PORT element, you can also use such ideal VSIN, ISIN components.Thank you for your reply. I new this way of finding THD so I started this way. But I could not figure out which method is right using THD directly from calculator or by using transient+DFT.
If I use PSS then I have to use the port source from analog lib but for fully differential structure. Do I have to place to two port : one at input negative input terminal and other at positive input terminal and two port at output. Can you help me in making the setup for fully differential structure because on different links I am just able to find single ended structure.
Thankyou
What is that ?? Joke ??Thanks Frankrose. I am using PSS but when I am sweeping the amplitude (-1 to 1V)its giving different THD. When on a fix amplitude lets say 100mV its giving different thd. The harmonics should be same whether I am sweeping or placing it fixed at one amplitude. While comparing it with thd function in calculator is giving totally different thd.
Wrong.Balun I thought is used for Rf circuits because its available in RF analog library.
Of course.I am working for low frequency will it be ok using balun in my case?
`include "constants.vams"
`include "disciplines.vams"
`ifdef CDS_MMSIM6_0_KERNEL_OR_LATER
//(* instrument_module *)
//(* ignore_hidden_state *)
`endif
module ideal_balun(c, d, p, n);
inout c, d, p, n;
electrical c, d, p, n;
parameter integer balun_en = 1; //0:Disable, Others:Enable
real vd1;
analog begin
if(balun_en != 0) begin
/*
V(p, c) <+ 0.5 * V(d);
V(c, n) <+ 0.5 * V(d);
I(d) <+ -0.5 * I(p, c);
I(d) <+ -0.5 * I(c, n);
*/
vd1 = 0.5 * V(d);
V(p) <+ V(c) + vd1;
V(n) <+ V(c) - vd1;
I(d) <+ -0.5 * (I(p) - I(n));
I(c) <+ -(I(p) + I(n));
end
else begin
V(d, p) <+ 0.0;
V(n) <+ 0.0;
end //if
end //analog
endmodule
Surely read.I have read about two tone and single tone while calculating thd.
What do you mean by "3rd order OTA" ?when I am using it in 3rd order OTA
What do you mean by "its" ?its THD is degraded to 35 db.
Wrong.I thought the THD will remain same equal to a single OTA even after designing filter?
It is natural.THD of the filter is degraded by cascading OTAs.
Everyone know such things except for you.Obtaining linearity in OTA is quite difficult.
And too good THD for a single OTA is quite difficult.
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