VCO gain estimation by capacitive measurement

摘要

Aspects of the present disclosure are generally directed to techniques and apparatus for estimating a gain of a VCO in a PLL. In certain aspects, the technique includes calculating a C-V characteristic of a varactor matched to another varactor in the VCO. The technique also includes estimating the gain of the VCO based on the C-V characteristic of the varactor, a tank inductance of the VCO, and an output frequency of the VCO. Aspects of the present disclosure allow for estimating the gain of the VCO while the PLL remains in operation.

主权项

1. An apparatus for estimating a gain of a VCO in a PLL, the apparatus comprising:
means for calculating a C-V characteristic of a varactor matched to another varactor in the VCO, wherein the means for calculating the C-V characteristic of the matched varactor comprises a means for applying a set of control voltages to the matched varactor; means for estimating the gain of the VCO based on the C-V characteristic of the matched varactor, tank inductance of the VCO, and an output frequency of the VCO, wherein estimating the gain of the VCO based on the C-V characteristic of the matched varactor allows the PLL to remain in operation during estimation, wherein the C-V characteristic is calculated using a DC coefficient and a second harmonic coefficient of a fast-Fourier transform (FFT) analysis; and means for computing an effective capacitance across the matched varactor to be a sum of the DC coefficient and half of the second harmonic coefficient.