Abstract: An all-pass type active circuit, realizable in the 8-12 GHz band has an inverting stage formed by a field effect transistor Q.sub.1, to whose gate the input signal V.sub.E is applied through a resistor R constituting the resistance of an RC network, and whose gate-source capacitance C.sub.GS is constitutes the capacitance C of the RC network. The parameters of a negative feedback branch inserted between the input V.sub.E and the output V.sub.S of the inverter, including a resistor R.sub.0 and a transmission line L.sub.0, are chosen so that the elements of Z=R.sub.0, l=.tau.v, R.sub.0 =2/G.sub.M0, where Z is the characteristic impedance of L.sub.0, l is the length of L.sub.0, v is the phase velocity of propagation, .tau. is the transit time of the electrons under the gate of Q.sub.1 and G.sub.M0 is the transconductance of Q.sub.1. The phase shift between V.sub.E and V.sub.S at an operating frequency .omega. is a function of the time constant .tau. of the RC network.