| 摘要 |
In one embodiment, this disclosure describes a frequency synthesizer for use in a wireless communication device, or similar device that requires precision frequency synthesis but small amounts of noise. In particular, the frequency synthesizer may include a phase locked loop (PLL) and an integrated voltage controlled oscillator (VCO). The frequency synthesizer may implement one or more amplitude calibration techniques prior to enabling the PLL. For example, an amplitude calibration unit may be used to selectively activate switched unit current sources within a tail current source of the VCO. In this manner, the amplitude the signal generated by the oscillator can be adjusted without requiring closed-loop amplitude monitoring or control.
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