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RC4200
PRODUCT SPECIFICATION
4
Notes:
1. Refer to Figure 6 for example.
2. The input circuits tend to become unstable at I
1
, I
2
, I
4
< 50
m
A and linearity decreases when I
1
, I
2
, I
4
> 250
m
A
(eq. @ I
1
= I
2
= 500
m
A, nonlinearity error
0.5%).
3. These specifications apply with output (I
3
) connected to an op amp summing junction. If desired, the output (I
3
) at pin (4) can
be used to drive a resistive load directly. The resistive load should be less than 700
W
and must be pulled up to a positive
supply such that the voltage on pin (4) stays within a range of 0 to +5V.
Frequency Response,
-3dB point
Supply Voltage
Supply Current
-18
4.0
-15
-9.0
4.0
-18
4.0
-15
-9.0
4.0
MHz
V
mA
I
1
= I
2
= I
4
= 150
m
A
T
A
= +25
°
C
Electrical Characteristics
(continued)
(Over operating temperature range, V
S
= -15V unless otherwise noted)
Parameters
Test Conditlons
4200A
Typ.
4200
Typ.
Min.
Max.
Min.
Max. Units
Applications Discussion
Current Multiplier/ Divider
The basic design criteria for all circuit configurations using
the RC4200 multiplier is contained in equation (1), that is,
The current-product-balance equation restates this as:
Figure 1. Current Multiplier/Divider
I
3
I
I
2
I
4
---------
=
I
1
I
2
I
3
I
4
6
=
65-4200-02
RC4200
+V
Z
R
1
–V
S
I
3
3
6
4
5
8
7
1
2
I
1
I
2
I
4
R
4
V
X
V
Y
+
+
+
R
2
A
Ammeter
I
1
=V
X
R
1
I
4
=V
Z
R
4
I
2
=V
Y
R
2
Dynamic Range and Stability
The precision dynamic range for the RC4200 is from +50
m
A
to +250
m
A inputs for I
1
, I
2
and I
4
. Stability and accuracy
degrade if this range is exceeded.
To improve the stability for input currents less than 50
m
A,
filter circuits (R
S
C
S
) are added to each input (see Figure 2).
Figure 2. Current Multiplier/Divider with Filters
Amplifier A1 is used to convert the I
3
current to an output
voltage.
Multiplier: Vz = constant
1
0
Divider: Vy = constant
1
0
65-4200-03
RC4200
V
Y
R
1
R
2
I
3
–
A1
+
R
O
V
O
3
6
4
5
8
7
1
2
I
2
I
1
I
4
R
4
V
X
R
S
R
S
C
S
C
S
–V
S
–V
S
+V
Z
+V
S
R
S
C
S
R
S
= 10k Ohms
C
S
= 0.005
μ
F