However, this article will show that the proper design of the tank circuit
allows the design to meet the phase noise specification.
The Q-factor of the tank circuit
is primarily limited by the inductor Q, which is approximately 10 at 5 to 6 GHz.
In the tank circuit
, total capacitance is the addition of the capacitances from a group of MOSFETs (N1 to N8) and varactors (D1 and D2).
The tank circuit
of a typical VCO has a parallel tuned circuit consisting of an inductance L, a fixed capacitance [C.
A VCO may be modeled as a tank circuit
and a positive feed back amplifier (Figure 2).
It is obvious that the oscillation frequency in the series tank circuit
Figure 5 shows the analysis of an LC tank circuit
for a Bluetooth VCO.
558 pF tank circuit
produces a rapid change in the reflection phase on either side of the resonant frequency, making it the best L/C combination for the proposed resonator.
In this example, R2 provides the negative feedback and the design uses a tank circuit
at the collector of Q2, which removes undesired capacitance and permits higher frequency operation.
L] represent the reflection coefficients of a resonant tank circuit
and matching network, respectively.