Design of variable loop gains of dual-loop DPLL

An approach to the derivation of variable loop gain sequences of dual-loop digital phase-locked loop (DPLL) is developed based on some modifications of the Kalman filtering formulation. It is shown that optimal loop gain sequences which are independent of measurement noise statistics can be obtained under a deterministic source model. Computer simulation results demonstrate that the adaptive dual-loop DPLL designed by using the proposed method is more robust to noise variations than the adaptive DPLL of Driessen (see ibid., vol.47, p.673-75, 1994).