01/99
B-41
IFN421, IFN422, IFN423
Dual N-Channel Silicon Junction Field-Effect Transistor
Absolute maximum ratings at T = 25¡C
¥ Very High Input Impedance
Differential Amplifiers
¥ Electrometers
A
Device Dissipation (Derate 3.2 mW/°C to 50°C)
400 mW
750 mW
– 65°C to 200°C
Total Device Dissipation (Derate 6 mW/°C to 150°C)
Storage Temperature Range
At 25°C free air temperature:
Static Electrical Characteristics
IFN421, IFN422, IFN423
Process NJ01
Test Conditions
I = – 1 µA, V = ØV
Min
Typ
Max
Unit
Gate Source Breakdown Voltage
Gate to Gate Breakdown Voltage
V
– 40
±40
– 60
V
V
(BR)GSS
G
DS
BV
I = – 1 µA, I = ØA, I = ØA
G D S
G1G2
– 1
– 1
pA
nA
pA
pA
V
V
= – 20V, V = ØV
GS
DS
Gate Reverse Current
Gate Operating Current
I
GSS
V
= – 20V, V = ØV
T = +125°C
GS
DS
A
– 0.25
– 250
– 2
V
= 10V, I = 30 µA
DS
D
I
G
V
= 10V, I = 30 µA
T = +125°C
DS
D
A
Gate Source Cutoff Voltage
Gate Source Voltage
V
– 0.4
60
V
= 10V, I = 1 nA
GS(OFF)
DS
D
V
– 1.8
1000
V
V
= 10V, I = 30 µA
GS
DS
D
Drain Saturation Current (Pulsed)
I
µA
V
= 10V, V = Ø V
DSS
DS
GS
Dynamic Electrical Characteristics
Common Source Forward Transconductance g
100
1500
3
µS
µS
V
= 10V, V = Ø V
f = 1 kHz
f = 1 kHz
f = 1 MHz
f = 1 MHz
f = 10 Hz
fs
DS
GS
Common Source Output Conductance
Common Source Input Capacitance
Common Source Reverse Transfer Capacitance
Equivalent Circuit Input Noise Voltage
g
V
= 10V, I = 30 µA
os
DS
D
C
3
pF
V
= 10V, V = Ø V
iss
DS
GS
C
1.5
70
pF
V
= 10V, V = Ø V
rss
DS
GS
e¯
20
nV/√Hz
V
= 10V, I = 30 µA
DS
D
N
V
= 10V, I = 30 µA
DS
D
Noise Figure
NF
1
dB
f = 10 Hz
R = 10 MΩ
G
Max - IFN421 IFN422 IFN423
Differential Gate Source Voltage
|V – V
|
10
15
25
mV
V
= 10V, I = 30 µA
GS1 GS2
DG
D
T = – 55°C
A
Differential Gate Source Voltage
With Temperature
|V – V
|
GS1 GS2
10
25
40
µV/°C
V
= 10V, I = 30 µA
T = 25°C
DG
D
B
∆T
T = 125°C
C
Min - IFN421 IFN422 IFN423
CMRR 90 80 80
Common Mode Rejection Ratio
dB
V
= 10V to 20V, I = 30 µA
DG
D
TOÐ78 Package
See Section G for Outline Dimensions
Pin Configuration
1 Source 1, 2 Drain 1, 3 Gate 1, 4 Case,
5 Source 2, 6 Drain 2, 7 Gate 2,
8 Omitted
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