
27-6 Electrical Variables
27.2 Charge Ampliers
e conversion of a charge, Q, into a measurement voltage involves at some stage the transfer of that
ch
arge
on
to
a re
ference
ca
pacitor,
C
r
. e voltage, V
r
, developed across the capacitor gives a measure of
th
e
ch
arge
as Q = V
τ
/C
r
. ere are two basic amplier congurations for carrying out such measure-
ments
u
sing
t
he
r
eference
c
apacitor
i
n
e
ither
a s
hunt
o
r
f
eedback
a
rrangement
.
27.2.1 Shunt Ampliers
Figure 27.4 shows a typical circuit in which the reference capacitor is used in a shunt mode. In this exam-
ple,
it is as
sumed
th
at
th
e
ch
arge
th
at
is to be me
asured
is th
e
re
sult
of th
e
in
tegrated ...