1. A frequency tuning device for use in a crystal oscillator circuit, comprising: a first fine tuning array of capacitors comprising an N-bit binary weighted switched capacitor network having a first plurality of switched capacitors of a first unit capacitance value; a second fine tuning array of capacitors comprising an M-bit thermometer coded switched capacitor network having a second plurality of switched capacitors of the first unit capacitance value; and a coarse tuning array of capacitors comprising a Q-bit binary weighted switched capacitor network having a third plurality of switched capacitors of a second unit capacitance value; wherein the first fine tuning array, the second fine tuning array and the coarse tuning array are coupled in parallel to produce a tuning capacitance.