Amplifier Noise

ENC amp = 115 e + 135 e x 1.5 ~ 315 e (1.5 pf max)

~ 230 e (0.8 pf min)

Thermal Noise

ENC Rbias = e/q √(tp Kt)/2Rbias ~ 150 e (1.5MΩ)

Shot Noise

ENC leak = e/q √(tp q Ileak)/4 ~ 3 e (15 pA measured)

~ 8 e (100 pA max spec)

ENC total = √(ENC amp)2 + (ENC Rbias)2 + (ENC leak)2

ENC total = √(315)2 + (150)2 + (8)2 ~ 350 e (max)