1. An adaptive voltage scaler (AVS), comprising: at least one delay circuit configured to receive an input signal and delay the input signal by a delay amount relating to at least one delay path of a functional circuit to produce a delay output signal; and an AVS circuit coupled to a database and responsive to the delay output signal, and configured to generate a voltage level setting signal based on a voltage level in the database associated with an operating frequency for the functional circuit and delay information in the delay output signal.