| 摘要 |
A capacitance switching element includes first and second capacitors connected in series by transistors. The gates of the transistors are biased by a first signal through one set of resistors, and the sources and drains are biased by a second signal through a second set of resistors. The signals are level-shifted and may be complimentary. To turn the element ON, the first signal may be set to VDD and the second signal may be set to zero. To turn the element OFF, the first signal may be set to a multiple of VDD/2 and the second signal may be set to the multiple plus one of VDD/2. When the element is used in an oscillator tuning circuit, the voltage stress on the transistors is reduced and the transistors may be fabricated with thin oxide. The oscillator may be used in a transceiver of a cellular access terminal. |
