amr87
Newbie level 5
spectre mixer
Hi
We all know that the mixer is just a multiplier that can be modeled mathematically as
V_out = m(t) * cos(wc*t)
where: m(t) is the input modulating signal
wc is the carrier frequency
if we are upconverting from an IF-frequency then
V_out = cos(w_IF*t) * cos(wc*t) = 0.5*(cos((wc+w_IF)t)+cos((wc-w_IF)t)))
And we are interested in only one sideband. So, after filtering the unwanted side band
V_out_filtered = 0.5*cos((wc+w_IF)t)
However, if we are upconverting directly from baseband
V_out = m(t)*cos(wc*t)
From which we can conclude that the conversion gain of direct upconversion mixer = 2*conversion gain of IF upconversion mixer
(Am I right at this point??)
Anyway, I am using spectre to simulate the direct up-conversion gain of a gilbert cell. I am also using PSS+PAC method.
So, does the resulting conversion gain is that corresponding to DIRECT CASE or the IF CASE????
Hi
We all know that the mixer is just a multiplier that can be modeled mathematically as
V_out = m(t) * cos(wc*t)
where: m(t) is the input modulating signal
wc is the carrier frequency
if we are upconverting from an IF-frequency then
V_out = cos(w_IF*t) * cos(wc*t) = 0.5*(cos((wc+w_IF)t)+cos((wc-w_IF)t)))
And we are interested in only one sideband. So, after filtering the unwanted side band
V_out_filtered = 0.5*cos((wc+w_IF)t)
However, if we are upconverting directly from baseband
V_out = m(t)*cos(wc*t)
From which we can conclude that the conversion gain of direct upconversion mixer = 2*conversion gain of IF upconversion mixer
(Am I right at this point??)
Anyway, I am using spectre to simulate the direct up-conversion gain of a gilbert cell. I am also using PSS+PAC method.
So, does the resulting conversion gain is that corresponding to DIRECT CASE or the IF CASE????