HI
I want to simulate a Chopper Amplifier, my circuit input source is current. The chopping frequency is 2.5k Hz, and the input signal frequency is 100 Hz. I use virtuoso version 6.1.4 (IC6.1.4.485) for simulation.
I test two setups and have some question about setups. I don't know which one is correct.
First, can I use general current source without substitute it with PORT for chopper amplifier for pnoise simulation? (I test this state(fig1,fig2), but I expect the flicker noise is being reduced on the low frequency and noise will translate to clock frequency while the result shows some spikes near input frequency as shown in FIG 3. I am uncertain about noise data. Is it correct?
fig3
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Second, in another test-bench I use PORT+VCCS for pnoise analysis to measure the input referred noise current of chopper amplifier. I read a document on Pnoise simulation on mixer simulation in
mixer simulation using spectre. In this tutorial, for pss+pnoise analysis all of the sources replaced with PORT. When I use PORT like the manual, I have to use VCCS to create current in circuit input. But when I do PSS+PNOISE analysis and plot the input noise using result ->direct plot the result is in V/sqrt(Hz), while I desired to plot the result in A/sqrt(Hz). In this state, since the PORT is in voltage the result for input noise is in is V/sqrt(Hz. I am not certain about PORT setting. In mixer manual the input port is DC and only clock port is signal. (I use sin voltage source in PORT)
I confused which one is correct. where I'm going wrong with the simulation setup? (In this case the result and setup are shown in fig 4)
fig4
best regard
sahand