| 摘要 |
A multiple frequency oscillator responds to a control signal to selectively produce an output signal having a first frequency or a second frequency. The oscillator includes a plurality of inverter stages (481-485) with the input of each inverter stage coupled to the output of another inverter stage. At least one of the inverter stages includes first and second transistors (50,51) having current paths connected in parallel, a third transistor (52) having a current path connected in series with the current paths of the first and second transistors (50, 51) between a first voltage source (Vdd) and the inverter stage output, and a fourth transistor (53) having a current path connected between the inverter stage output and a second voltage source (Vss). The control electrodes of the first, third, and fourth transistors (50, 52, 53) are connected to the input of the inverter stage. A control signal controls the conductivity of the second transistor (51) to select the frequency of output signal of the oscillator (44).
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