A variation of the Colpitts crystal oscillator based on a modification of the Butler structure and capable of driving the quartz crystal when the power supply has a low voltage value is presented. The addition of a grounded inductor with an appropriate value to the Colpitts circuit, without the need of a series resonance branch, is a non-bridged single solution that improves the excitation gradient of the crystal and, moreover, the spectral purity of the generated wave is enhanced. Also, it is reduced the circuit sensitivity with respect to crystal parameters. The resulting circuit requires only a reduced number of components, thus being suitable to be implemented as analogue integrated circuits.