ABSTRACT
This chapter describes the principal sources of electric noise and discusses methods for the measurement of noise. The notations for voltages and currents correspond to the following conventions: dc quantities are indicated by an upper-case letter with upper-case subscripts, e.g.,
V
. Instantaneous small-signal ac quantities are indicated by a lower-case letter with lower-case subscripts, e.g.,
v
. The mean-square value of a variable is denoted by a bar over the square of the variable, e.g., , where the bar indicates an arithmetic average of an ensemble of functions. The root-mean-square or rms value is the square root of the mean-square value. Phasors are indicated by an upper-case letter and lower case subscripts, e.g.,
V
. Circuit symbols for independent sources are circular, symbols for controlled sources are diamond shaped, and symbols for noise sources are square. In the evaluation of noise equations, Boltzmann’s
constant is
k
= 1.38
¥
J K
and the electronic charge is
q
= 1.60
¥
C. The standard temperature is denoted by
T
and is taken to be
T
= 290 K. For this value, 4
kT
= 1.60
¥
J and the thermal voltage is
V
=
kT
/
q
= 0.025 V.
