Development status of the microcomputer compensated crystal oscillator

The design of the MCXO eliminates the three primary obstacles to stability of the conventional temperature compensated crystal oscillator (TCXO). These are: (1) errors in measuring the crystal temperature; (2) use of a fundamental mode AT instead of an overtone SC cut crystal; and, (3) hysteresis and aging associated with pulling the crystal. As a result, the MCXO achieves about 30 times better stability than the best TCXOs. In this paper we review the MCXO design technology, describe the Q-Tech MCXO, QT2001, and describe some future developments.