Here is a specific example, with 4 millivolt peak-peak signal of 1million ohm source impedance, driving an Analog-Digital Converter of 10pF input capacitance.
The interferer is MCU clock, located 1 millimeter away from the signal trace.
With interference[the screen shoot illustrates this case], the SNR is -22dB (that MCU trash is 12X stronger than the 4milliVolt signal. To compute this, the "Gargoyles" button is checked, also the far-right "I/C" button is checked, and then "Update" button is clicked.
Without interference ("Gargoyles" turned off) SNR is +39dB (signal nearly 100X stronger than the ----- random thermal noise ----- measurement floor.
Thus the presence of Efield interferer caused ---- in this case ---- 60dB change, or 1,000:1 change, in the Signal Noise Ratio.
and here is the (editable; you got here by clicking OFF the global-trace mode and then clicking on the "trace wizard") default dimensions of the trace used as the vulnerable signal trace, the victim of Efield trash injection, modeled in this version as parallel-plate capacitance coupling.
How does SignalChain Explorer work? By modeling the Signal Chain, the tool has access to the NODE IMPEDANCE; when a current (displacement current, arriving from capacitive interference) enters any node, the error voltage is simply Current * Node_Impedance.
In this example, the signalChain has only 1 node available to respond to interference: the point of connection between Sensor Output and the ADC input.
The default Efield interferer is the MCU clock, defaulted to 1mm distance from the signal trace, with 100MHz clock rate and 2.5 volt peak-peak voltage.
The sensor has Zout of 1Million ohms. The ADC has 100 ohms Rin and 10pF, a time constant of 1nanosecond and F3dB of 160MHz; the MCU clock energy blasts onto the ADC, attenuated only by the capacitive-division of the two series capacitors:
1) the parallel-plate coupling model used between the two traces (MCU trace and
signal chain trace)
2) the node capacitance, dominated by 10pF of the ADC sampling capacitor.