A Q-invariant active resonator

A new RC-amplifier resonator has a pole Q which is invariant under passive element drift. The differential sensitivities S
x
^Q
are all zero. The macroscopic sensitivities give ΔQ/Q=-12 ppm for ΔZ/Z=1 percent. Thermal coefficients of R and C can thus be chosen for constant center frequency in several ways without affecting the Q stability.