| 摘要 |
<p>A multi-crystal controlled oscillator (10) and method includes a first crystal resonator (11), second crystal resonator (14), oscillator circuit (23), and a switch (29). The switch (29) is coupled between the first crystal resonator (11) and the oscillator circuit (23) and between the second crystal resonator (14) and the oscillator circuit (23), and electrically couples either the first (11) or the second crystal resonator (14) to the oscillator circuit (23) in response to a crystal select input (XTAL SELECT). The oscillator (10) includes a first pull-down FET (72) coupled between the first crystal resonator (11) and an electrical ground (18) and a second pull-down FET (74) coupled between the second crystal resonator (14) and electrical ground (18) such that when the switch (29) electrically couples the first crystal resonator (11) to the oscillator circuit (23) the second pull-down FET (74) electrically grounds the second crystal resonator (14), and when the switch (29) electrically couples the second crystal resonator (14) to the oscillator circuit (23) the first pull-down FET (72) electrically couples the first crystal resonator (11) to the electrical ground (18).</p> |
