| 摘要 |
A voltage controlled oscillator (VCO) generating an output voltage. The VCO has a transconductance amplifier, a capacitor, a comparator, and a switch. The transconductance amplifier receives an input voltage and outputs an output current and has a control terminal receiving a control voltage. The capacitor is coupled between the output of the transcondcutance amplifier and a signal ground. The comparator has a first input terminal coupled to the output of the transcondcutance amplifier, a second input terminal receiving a reference voltage, and an output terminal providing the output voltage. The switch is coupled between the output of the transconductance amplifier and the signal ground and controlled by the output voltage. Phase lock loops (PLLs) including the VCO, a filter with Gm/C self-tuning and a method of tuning Gm/C are disclosed as well.
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