N-Channel Dual JFET CORPORATION U421 – U426 FEATURES • Ultra Low Input Bias Current . . . . . . . 250 Fempto Amps • Low Operating Current • Tight Matching Characteristics APPLICATIONS Low Leakage FET Input Op Amps • Ultra • Electrometer • Infrared Detectors • pH Meters 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 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 6 7 1 BOTTOM VIEW CJ4 C G2 D2 S2 G1 D1 S1 U421 – U426 CORPORATION ABSOLUTE MAXIMUM RATINGS (TA = 25oC unless otherwise noted) Total Device Dissipation, TA = 25oC (Derate 6.0 mW/ oC to 150oC) . . . . . . . . . . . . . 750 mW Storage Temperature Range . . . . . . . . . . . . . -65oC to +150oC 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 U421-3 CHARACTERISTIC U424-6 MIN TYP MAX MIN TYP -60 -40 -60 UNIT MAX TEST CONDITIONS STATIC BVGSS Gate-Source Breakdown Voltage -40 BVG1G2 Gate-Gate Breakdown Voltage ±40 ±40 (1) IGSS Gate Reverse Current IG Gate Operating Current VGS (off) Gate-Source Cutoff Voltage (1) VGS Gate-Source Voltage IDSS Saturation Drain Current V IG = -1µA, VDS = 0 IG = -1µA, ID = 0, IS = 0 1.0 3.0 pA T = +25oC 1.0 3.0 nA T = +125 oC .25 0.5 .250 -500 -0.4 -2.0 -0.4 -2.0 60 1000 60 1800 300 1500 300 1500 -1.8 pA V -2.9 µA T = +25oC T = +125 oC VGS = -20V, VDS = 0 VDG = 10V, ID = 30µA VDS = 10V, ID = 1nA VDG = 10V, ID = 30µA VDS = 10V, VGS = 0 DYNAMIC gfs Common-Source Forward Transconductance gos Common-Source Output Conductance 10 10 Ciss Common-Source Input Capacitance 3.0 3.0 Crss Common-Source Reverse Transfer Capacitance 1.5 1.5 gfs Common-Source Forward Transconductance gos Common-Source Output Conductance en Equivalent Short Circuit Input NF SYMBOL 120 350 120 CHARACTERISTIC 70 20 70 nV/ Hz 10 1.0 U421,4 f = 1kHz 3.0 10 Noise Figure f = 1MHz pF 350 3.0 20 f = 1 kHz VDS = 10V, VGS = 0 1.0 U422,5 dB U423,6 MIN TYP MAX MIN TYP MAX MIN TYP MAX UNIT VDG = 10V, ID = 30µA f = 10Hz f = 1kHz f = 10 Hz RG = 10 MΩ TEST CONDITIONS MATCH | VGS1-VGS2 | Differential Gate-Source Voltage 10 15 25 mV | VGS1-VGS2 | Differential Gate-Source Voltage Change with Temperature (2) ∆T 10 25 40 V/ oC CMRR Common Mode Rejection Ratio (3) 90 NOTES: 1. Approximately doubles for every 10oC increase in TA. 2. Measured at endpoints TA, TB and TC. 95 80 90 3. CMRR = 20log 10 80 V 90 [VGS1DD -VGS2 ] 4. Case lead not connected. dB VDD = 10V. VDG = 10V, ID = 30µA VDG = 10V, ID = 30µA, TA = -55oC, TB = 25oC, TC = 125oC ID = 30µA, VDG = 10 to 20 V