COIL-LESS OVERTONE CRYSTAL OSCILLATOR

An overtone crystal oscillator including a crystal, multiple amplifiers and an RC network. The crystal has a fundamental resonance frequency and at least one overtone resonance frequency. The amplifiers are coupled in series between terminals of the crystal and the RC network is coupled to the amplifiers. The amplifiers and the RC network are collectively configured to suppress oscillation of the crystal at the fundamental resonance frequency and to enable oscillation at an overtone resonance frequency of the crystal. The amplifiers and the RC network may be configured to cause a phase shift between the fundamental resonance frequency and the overtone resonance frequency. The overtone resonance frequency may be any odd harmonic of the fundamental frequency, such as a third overtone of the crystal. The overtone crystal oscillator may be integrated with CMOS processes and does not require an inductor to suppress the fundamental mode of oscillation.