Document
N-Channel Dual JFET
CORPORATION
U421 – U426
FEATURES DESCRIPTION The Calogic U421 Series are Dual N-Channel JFETs on a monolithic structure designed specifically for very high input impedance for differential amplification and impedance matching. This series features ultra low input bias current (250 fempto amps, U421) while offering high gain at low operating currents and tight matching characteristics. These devices are available in chip form for hybrid designs as well as a hermetic TO-78 package. ORDERING INFORMATION Part Package Temperature Range U421-U426 TO-78 Hermetic Package -55oC to +150oC XU421-U426 Sorted Chips in Carriers -55oC to +150oC
• Ultra Low Input Bias Current . . . . . . . 250 Fempto Amps • Low Operating Current • Tight Matching Characteristics
Low Leakage FET Input Op Amps • Ultra • Electrometer • Infrared Detectors • pH Meters
APPLICATIONS
PIN CONFIGURATION
TO-78
1 2 3 4 5 6 7
SOURCE 1 DRAIN 1 GATE 1 CASE/BODY SOURCE 2 DRAIN 2 GATE 2
4 5 3 2 1
6 7
BOTTOM VIEW
C S2 G1 D2 D1 G2 S1
CJ4
U421 – U426
CORPORATION
ABSOLUTE MAXIMUM RATINGS (TA = 25oC unless otherwise noted) Gate-to-Gate Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . ±40V Gate-Drain or Gate-Source Voltage . . . . . . . . . . . . . . . . -40V Gate Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA Device Dissipation (Each Side), TA = 25oC (Derate 3.2 mW/ oC to 150oC) . . . . . . . . . . . . . . 400mW ELECTRICAL (25oC Unless otherwise noted) noted) ELECTRICAL CHARACTERISTICS CHARACTERISTICS (25oC unless otherwise
SYMBOL STATIC BVGSS BVG1G2 IGSS Gate-Source Breakdown Voltage Gate-Gate Breakdown Voltage Gate Reverse Current
(1)
Total Device Dissipation, TA = 25oC (Derate 6.0 mW/ oC to 150oC) . . . . . . . . . . . . . 750 mW Storage Temperature Range . . . . . . . . . . . . . -65oC to +150oC
CHARACTERISTIC
U421-3 MIN -40 ±40 1.0 1.0 TYP MAX -60 MIN -40 ±40
U424-6 TYP -60 MAX
UNIT
TEST CONDITIONS
V 3.0 3.0 0.5 -500 pA nA pA
IG = -1µA, VDS = 0 IG = -1µA, ID = 0, IS = 0 T = +25oC T = +125 oC T = +25oC T = +125 oC VGS = -20V, VDS = 0 VDG = 10V, ID = 30µA
IG VGS (off) VGS IDSS DYNAMIC gfs gos Ciss Crss gfs gos en NF
Gate Operating Current
(1)
.25 .250
Gate-Source Cutoff Voltage Gate-Source Voltage Saturation Drain Current
-0.4
-2.0 -1.8
-0.4
-2.0 -2.9
V µA
VDS = 10V, ID = 1nA VDG = 10V, ID = 30µA VDS = 10V, VGS = 0
60
1000
60
1800
Common-Source Forward Transconductance Common-Source Output Conductance Common-Source Input Capacitance Common-Source Reverse Transfer Capacitance Common-Source Forward Transconductance Common-Source Output Conductance Equivalent Short Circuit Input Noise Figure
300
1500 10 3.0 1.5
300
1500 10 3.0 1.5 pF VDS = 10V, VGS = 0
f = 1 kHz
f = 1MHz
120
350 3.0 20 10 1.0 70
120
350 3.0 20 10 1.0 70 nV/ Hz dB VDG = 10V, ID = 30µA
f = 1kHz f = 10Hz f = 1kHz f = 10 Hz RG = 10 MΩ
SYMBOL MATCH
CHARACTERISTIC
U421,4
U422,5
U423,6
MIN TYP MAX MIN TYP MAX MIN TYP MAX 10 10 90 95 80 90 15 25 80 90 25 40
UNIT
TEST CONDITIONS
| VGS1-VGS2 | Differential Gate-Source Voltage | VGS1-VGS2 | Differential Gate-Source Voltage Change with Temperature (2) ∆T CMRR Common Mode Rejection Ratio (3)
mV V/ oC dB
VDG = 10V, ID = 30 µA VDG = 10V, ID = 30µA, TA = -55oC, TB = 25oC, TC = 125oC ID = 30µA, VDG = 10 to 20 V
NOTES: 1. Approximately doubles for every 10oC increase in TA. 2. Measured at endpoints TA, TB and TC.
3. CMRR = 20log 10
[VGS1DD -VGS2 ]
V
VDD = 10V.
4. Case lead not connected.
.