Local oscillator and equivalent circuit a

Local oscillators mostly use common collector circuits above 1GHz, which are not prone to low-frequency self-oscillation. Usually the local oscillator signal
is added to the mixer through a buffer amplifier stage to reduce the impact of mixing on the frequency stability of the local oscillator. Shown is the local oscillator and
equivalent circuit, which is a common collector capacitor feedback oscillation circuit . When the value of the tuning voltage changes, the capacitance of the varactor connected in the oscillation circuit changes, resulting in a change in the oscillation frequency, thus enabling channel selection.