| 摘要 |
The use of a control circuit (160) with either a programmable divider or divider(s) (190) and multiplexer (200) guarantees that, irrespective of the process variations, a voltage controlled oscillator has a low gain Vin-Fout characteristic in the desired frequency range. Low-gain voltage controlled oscillators are fundamental building blocks of low-jitter phase-locked loop (PLL) systems. The programmable divider/divider(s) (190) and multiplexer (200) are placed at an output of a current controlled oscillator(s) (180). A control circuit (160) defines the optimum current range(s) in the current controlled oscillator(s) (180). In the case of when a programmable divider is used, the control circuit (160) keeps changing the division ratio of the programmable divider until the PLL eventually achieves the "locked" state. When divider(s) and a multiplexer (200) are used, the control circuit (160) keeps changing the selected multiplexer input until the "locked" state has been achieved. Only one current controlled oscillator is achieve at any one time. This control circuit could be for example an auto-lock circuit.
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