One of the attractive aspects of a 2-port probe is the browser type functionality to measure PDN impedance of any board.
In lecture "2-Port Impedance Measurement Part-2", you measure the PDN impedance by putting the 2-port 4-point (Kelvin) across two capacitor pads. This means either the capacitors were removed, or the pads were added extra during design time.
(1) Can we measure the PDN impedance without removing the decoupling capacitors, since we may not have the luxury to remove them. We will be measuring the PDN impedance or capacitor impedances? How much error does measuring across capacitors create instead of just the pads?
(2) For the 4-point probe, we need two capacitor pads side-by-side, correct?