MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第552页

MIL-STD-883F METHOD 4001.1 22 March 1989 2 3.2 Input offs et cur rent . This has a meaning for diff erenti al input ampl ifi ers onl y. 3.2.1 Differ ential i nput ampli fier . The tes t fi gure is shown on fi gure 4001-1…

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MIL-STD-883F
METHOD 4001.1
22 March 1989
1
METHOD 4001.1
INPUT OFFSET VOLTAGE AND CURRENT AND BIAS CURRENT
1. PURPOSE
. This method establishes the means for measuring input bias current and the offset in voltage and current
at the input of a linear amplifier with differential inputs. Offset voltage may also be pertinent in some single input amplifiers.
Input bias current will also be measured in this procedure.
1.1 Definitions
. The following definitions shall apply for the purpose of this test method.
1.1.1 Input offset voltage (V
IO
). That dc voltage which must be applied between the input terminals through two equal
resistances to force the quiescent dc output to zero or other specified level V
QO
, generated by V
QI
.
1.1.2 Input offset voltage drift (DV
IO
). Input offset voltage drift is the ratio of the change of input offset voltage to the
change of the circuit temperature.
IO
IO
DV
=
V
T
∆
∆
1.1.3 Input offset current (I
IO
). The input offset current is the difference between the input bias currents entering into the
input terminals of a differential input amplifier required to force the output voltage to zero or other specified level (V
QO
).
1.1.4 Input offset current drift (DI
IO
). The input offset current drift is the ratio of the change of input offset current to the
change of circuit temperature.
IO
IO
DI
=
I
T
∆
∆
1.1.5 Input bias current (I
IB
). The input bias currents are the separate currents entering into the two input terminals of a
balanced amplifier, specified as +I
IB
and -I
IB
. The bias current in a single ended amplifier is defined as I
IB
.
1.1.6 Input offset voltage adjust (±V
IO adj
). Bias adjustment which produces maximum offset at the output.
2. APPARATUS
. The apparatus shall consist of appropriate test equipment capable of measuring specified parameters
and an appropriate test fixture with standard input, output, and feedback resistances.
3. PROCEDURE
. The test figures show the connections for the various test conditions. An op amp null loop test figure is
also shown as an alternate test setup. R
2
shall be no larger than the nominal input impedance nor less than a value which
will load the amplifier (10 x Z
OUT
). Let R
2
/R
1
= 100 or 0.1 x (open loop gain), whichever is smaller. Recommended
stabilization and power supply decoupling circuitry shall be added. R
3
shall be no larger than the nominal input impedance.
For methods using the null loop circuit, assume all switches (relays) normally closed.
3.1 Input offset voltage
.
3.1.1 Differential input amplifier
. The test setup is shown on figure 4001-1. Input offset voltage V
IO
= (R
1
/R
2
) (E
O
- V
QI
).
Switches S
1
and S
2
are closed for this test.
3.1.2 Single ended inverting amplifier
. The test setup is shown on figure 4001-2. Input offset voltage V
IO
= (R
1
/R
2
)
(E
O
- V
QI
). Switch S is closed for this test.
3.1.3 Single ended noninverting amplifier
. The test figure is shown on figure 4001-3. V
IO
= (R
1
/R
2
) (E
O
- V
QI
). Switch S is
closed for this test.
3.1.4 Differential input amplifier
. This is an alternative method using the null loop circuit of figure 4001-4, in which all
switches are closed. Set V
C
to zero. Measure E
O
. V
IO
= (R
1
/R
2
)(E
O
).
MIL-STD-883F
METHOD 4001.1
22 March 1989
2
3.2 Input offset current. This has a meaning for differential input amplifiers only.
3.2.1 Differential input amplifier
. The test figure is shown on figure 4001-1. Measure E
01
with S
1
and S
2
closed, measure
E
02
with S
1
and S
2
open.
IO
1
2
01 02
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
3.2.2 Differential input amplifier using null loop
. The test setup is shown on figure 4001-4, S
1
and S
4
are closed, set
V
C
= 0. Measure E
01
as in 3.1.4. Open S
2
and S
3
and measure E
02
.
IO
1
2
02 01
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
3.3 Input bias current
.
3.3.1 Differential input amplifier
. The test figure is shown on figure 4001-1. Measure E
01
with S
1
and S
2
closed, measure
E
02
with S
1
closed and S
2
open. Measure E
03
with S
1
open and S
2
closed.
IB+
1
2
01 02
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
IB-
1
2
01 03
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
3.3.2 Single ended inverting amplifier
. The test figure is shown on figure 4001-2. Measure E
01
with S closed, measure
E
02
with S open.
IB
1
2
01 02
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
3.3.3 Single ended noninverting amplifier
. The test figure is shown on figure 4001-3. Measure E
01
with S closed.
Measure E
02
with S open.
IB
1
2
01 02
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
3.3.4 Differential input amplifier using null loop
. The test setup is shown on figure 4001-4. Set V
C
to zero with S
1
and S
4
closed. Measure E
01
with S
2
closed and S
3
closed. Measure E
02
wth S
2
open and S
3
closed. Measure E
03
with S
2
closed
and S
3
open.
IB+
1
2
03 01
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
IB-
1
2
02 01
3
I
=
R
R
E
-
E
R
⎛
⎝
⎜
⎞
⎠
⎟
MIL-STD-883F
METHOD 4001.1
22 March 1989
3
3.4 Input offset voltage drift. Measurement of V
IO1
is made at temperature T
1
in accordance with 3.1 and a second
measurement at T
2
of V
I02
is made at the second temperature.
IO
IO2 IO1
21
DV
=
V
-
V
T
-
T
3.5 Input offset current drift
. Measurement of I
I01
is made at temperature T
1
and I
I02
at temperature T
2
in accordance with
3.2.
IO
IO2 IO1
21
DI
=
I
-
I
T
-
T
3.6 Adjustment for input offset voltage
. Use the value of E
0
for 3.1.4. Measure E
01
with the offset null voltage (V
ON
) set to
the positive extreme.
IO Adj O 01
1
2
V
(+) = (
E
-
E
)
R
R
Measure E
02
with the offset null voltage (V
ON
) set to the negative extreme:
IO Adj O 02
1
2
V
(-) = (
E
-
E
)
R
R
NOTE: V
ON
may be implemented using a combination of resistors to obtain the proper voltage across the offset null
terminals. This determination shall be based on the device under test (DUT) specifications.
4. SUMMARY
. The following details shall be specified in the applicable acquisition document for specified values of R
1
,
R
2
, and R
3
, R
4
, R
5
, R
L
, and ±V
CC
of the nulling amplifier.
a. V
IO
maximum.
b. DV
IO
maximum at specified temperature(s).
c. I
IO
maximum when applicable.
d. DI
IO
maximum, when applicable at specified temperature(s).
e. I
IB+
and I
IB-
maximum at specified temperature(s).
f. V
QI
and V
QO
, when applicable, at specified temperature(s).
g. ±V
IO Adj
at specified temparature(s).
h. Test temperature(s). Unless otherwise specified, all parameters shall be measured at the minimum and maximum
specified operating temperature and at +25°C ambient.