Noise Figure of Capacitor


Trans-impedance of the circuit,

    \[G_{z} = \frac{v_o}{i_s} = {R_s \over 1 + sCR_s}\]

Power gain, G = |G_z|^2 = { R_s^2 \over 1 + (\omega C R_s)^2 }

Noise added by the capacitor to ouput, N_A = 0

Noise factor, F = 1 + {N_A \over N_i} = 1 + { 0 \over GN_i} = 1

Therefore noise figure of a capacitive load, NF = 10 \log (F) = 0

Figure 3. Noise figure computation of capacitive load >> Norton equivalent representation >> Equivalent circuit for noise figure calculation

The noise added by the losses elements like inductor and capacitor at the output is zero. Hence the noise figure is 0dB.

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