raja.cedt wrote on Sep 12th, 2009, 6:50am:hi,
can any body please tell me why active load thermal noise is more than passive resistor noise. From math i got to know that noise depends on ratio of V and I. But i am expecting some intutive answer.
thanks,
Rajasekhar.
Hi,
An active load is a voltage-dependent resistance which introduces non-linearity effects into the circuit ( Total Harmoic Distortion increases ). also as in one of the replies above, an active device introduces thermal noise whose magnitude is proportional to γ - a parameter that scales based on channel lengths. [ nearly 2/3 for long channel , nearly 1 for short channel ] Also, flicker corners vary with different processes, that also decides the total thermal noise contribution. Accounting for all these factors, total noise from an active load should generally be more than its passive counterpart.
Hope this extends the above post by MarcoC & explains your query,
thanks,
Mayank.