The MK3721 is ICS/MicroClock's lowest cost, low jitter, high performance 3.3 volt VCXO designed to replace expensive VCXO modules. The on-chip Voltage Controlled Crystal Oscillator accepts a 0 to 3.3 V input voltage to cause the output clocks to vary by 100 ppm. Using ICS/MicroClock's patented VCXO techniques, the device uses an inexpensive external pullable crystal in the range of 16.2 - 28 MHz to produce a VCXO output clock at that same frequency.