Low crosstalk opamps (Burr-Brown)
You will always have HEAT interactions. Even if the layout of each front_end diffpair is the legendary cross_coupled quad, the metallization will have imbalances; given aluminum has about the same specific heat and thermal conductivity of silicon, there will be thermal interactions. The thermal timeconstant of 1mm (1,000 micron) silicon cube is 0.0114 seconds (11 milliSeconds), thus low base tones will be interacting via the silicon substrate.
And, with the shared VDD/GND pins, the high-frequency inductive bounce that far exceeds what Power Supply Rejection can exclude, will always intrude directly thru the output transistors to the I_hope_this_is_clean Vout.
And there will be electric fields thru the black plastic epoxy, particularly to/from the large_area compensation capacitors.
And magnetic fields, as &quot;high currents&quot; (10mA/10 nanoseconds for fast opamps, not audio) are predictable, but the conductive silicon substrate will attenuate.
And package pin_to_pin mutual inductance. Let us compute that: 10mA/10 microSeconds to support a 16KHz tone. With 1 nanoHenry pin_to_pin inductance.
Shall we assume 1 microvolt is acceptable level of crosstalk?
V = L * dI/dT = 1e-9 * (0.01amp/10uS) = 1e-9 * 1e-2/1e-5 = 1e-9 * 1e+3
V = 1e-6
Thus for higher audio tones, driving 10 milliAmps, the interaction is at 1uV level. What to do?