A programmable crystal oscillator is provided having a memory for storing frequency-defining parameters. Typically, one of these parameters is used to program an adjustable capacitive load circuit coupled to a crystal to thereby adjust the crystal source frequency. Additional parameters are used to program...http://www.google.com.au/patents/US5952890?utm_source=gb-gplus-sharePatent US5952890 - Crystal oscillator programmable with frequency-defining parameters
