At the heart of nearly all digital electronics are timing signals. Fixed frequency clocks are necessary for microprocessors, ADCs, DACs, switching regulators, signal-generators, and many other synchronized electronics. With the prevalence of high speed computers, one often thinks of MHz and GHz clock frequencies, but clock frequencies ranging from femtoseconds to hours, days and even longer are commonly used in electronics today. The digital nature of clock signals make them convenient as a method to encode and distribute information. In particular, frequency or pulse width modulated clock signals are commonly used to control electronic devices, such as motor speed, heater power, and LED intensity. With the use of digital isolators or transformers, these modulated signals are also ideal for transmitting information across an electrical isolation barrier. Asynchronous timing signals are also important in electronics for event timing. For example, accurate pulse generation and delay timing is critical for sequencing, delaying or activating devices.