the paper deals with the analogue frequency filter synthesis using the M-C signal flow graph theory. Individual forms of the characteristic equation or of the transfer function denominator are described that guarantee the possibility of controlling the quality factor Q independently of the characteristic or cut-off frequency, with the help of active elements. The design procedure is shown on the design of a frequency filter working in the current-mode with current active elements PCA and CMI. The behaviour of the proposed filter has been verified by simulations in the OrCAD program and also by experimental measurements.