A 10-MHz Micromechanical Resonator Pierce Reference Oscillator for Communications

Abstract

A modified Pierce circuit topology has been used to first demonstratea 9.75 MHz mu mechanical resonator reference oscillator, then toassess the ultimate frequency stability of such an oscillator viaaccurate measurement of its close-to-carrier phase noise, which seemsto exhibit an unexpected 1/f/sup 3/ dependence that limits the phasenoise to -80 dBc at a 1 kHz offset from the carrier - a value thatmust be improved before use in most communications applications.Through theoretical analysis, this 1/f/sup 3/ dependence seems toderive from aliasing of active circuit 1/f noise onto the carriercaused by nonlinearity in the capacitive transducer of the mu mechanicalresonator. (9 References)