A circuit is described that detects high and low frequencies and additional clock frequencies and outputs a signal that indicates a high, a low frequency or an additional mode. When in the low frequency low frequency mode signals are regenerated free of any high frequency signals from appearing on the filtered low frequency clock line. The rising and falling edges of the input clock are low pass filtered separately and then combined to generate a low frequency clock or the additional input clock and that retains the input clock pulse width and duty cycle.