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.

Analog/RF IntgCkts