What value of port impedance should be in Noise simulation with Cadence Spectre?
时间：04-06
整理：3721RD
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Hi guys,
I've gotten something unsure about noise factor. Hope for help here.
The Noise Factor is defined as below.
N = (Na+G*Ns)/(G*Ns).
Different Ns produces different N. And in Cadence spectre, the noise source is usually a port. The impedance of the port provides the thermal noise 4kTRB V^2, which is related to the value of R.
Q1: What value of R should be set?
Q2: If R=50 Ohm, why?
Q3: If R=Rout of the preceding device, then noise factor of the DUV(Device Under Test) is dependent on different source impedances. So noise factor is not a general performance factor of DUV for comparison, isn't it?
Anyone can help me?
Thanks in advance.
I've gotten something unsure about noise factor. Hope for help here.
The Noise Factor is defined as below.
N = (Na+G*Ns)/(G*Ns).
Different Ns produces different N. And in Cadence spectre, the noise source is usually a port. The impedance of the port provides the thermal noise 4kTRB V^2, which is related to the value of R.
Q1: What value of R should be set?
Q2: If R=50 Ohm, why?
Q3: If R=Rout of the preceding device, then noise factor of the DUV(Device Under Test) is dependent on different source impedances. So noise factor is not a general performance factor of DUV for comparison, isn't it?
Anyone can help me?
Thanks in advance.