We present a simple and fast technique for the design of ring resonator-based optical filters. The technique is based on tapering the ring scattering parameters to achieve the optimal filter response. A perturbation method is developed for the linearization of the resulting design problem. The design problem is then formulated as an optimization problem. The optimal filter design is achieved by solving a constrained linear least square problem. This optimization problem can be solved efficiently to get the global optimal design. Our technique has been verified using different proposed targeted filter responses.