JFET Amplifiers
N–Channel
MAXIMUM RATINGS
Rating Symbol Value Unit
Drain–Source Voltage VDS 25 Vdc
Gate–Source Voltage VGS 25 Vdc
THERMAL CHARACTERISTICS
Characteristic Symbol Max Unit
Total Device Dissipation(1)
TA = 25°C
Derate above 25°C
PD225
1.8
mW
mW/°C
Thermal Resistance Junction to Ambient RJA 556 °C/W
Total Device Dissipation
Alumina Substrate,(2) TA = 25°C
Derate above 25°C
PD300
2.4
mW
mW/°C
Thermal Resistance Junction to Ambient RJA 417 °C/W
Junction and Storage Temperature TJ, Tstg –55 to +150 °C
DEVICE MARKING
BFR30LT1 = M1; BFR31LT1 = M2
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted)
Characteristic Symbol Min Max Unit
OFF CHARACTERISTICS
Gate Reverse Current (VGS = 10 Vdc, VDS = 0) IGSS — 0.2 nAdc
Gate Source Cutoff Voltage (ID = 0.5 nAdc, VDS = 10 Vdc) BFR30
BFR31 VGS(OFF) —
—5.0
2.5 Vdc
Gate Source Voltage (ID = 1.0 mAdc, VDS = 10 Vdc) BFR30
BFR31
(ID = 50 Adc, VDS = 10 Vdc) BFR30
BFR31
VGS –0.7
—
—
—
–3.0
–1.3
–4.0
–2.0
Vdc
1. Device mounted on FR4 glass epoxy printed circuit board using the recommended footprint.
2. Alumina = 0.4 x 0.3 x 0.024 in. 99.5% alumina.
ON Semiconductor
Semiconductor Components Industries, LLC, 2001
March, 2001 – Rev. 1 361 Publication Order Number:
BFR30LT1/D
BFR30LT1
BFR31LT1
CASE 318–08, STYLE 10
SOT–23 (TO–236AB)
12
3
1 DRAIN
2 SOURCE
3
GATE
BFR30LT1 BFR31LT1
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362
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted) (Continued)
Characteristic Symbol Min Max Unit
ON CHARACTERISTICS
Zero–Gate–Voltage Drain Current (VDS = 10 Vdc, VGS = 0) BFR30
BFR31 IDSS 4.0
1.0 10
5.0 mAdc
SMALL–SIGNAL CHARACTERISTICS
Forward Transconductance
(ID = 1.0 mAdc, VDS = 10 Vdc, f = 1.0 kHz) BFR30
BFR31
(ID = 200 Adc, VDS = 10 Vdc, f = 1.0 kHz) BFR30
BFR31
yfs1.0
1.5
0.5
0.75
4.0
4.5
—
—
mAdc
Output Admittance
(ID = 1.0 mAdc, VDS = 10 Vdc, f = 1.0 kHz) BFR30
(ID = 200 Adc, VDS = 10 Vdc) BFR31
yos40
20 25
15
Adc
Input Capacitance (ID = 1.0 mAdc, VDS = 10 Vdc, f = 1.0 MHz)
(ID = 200 Adc, VDS = 10 Vdc, f = 1.0 MHz) Ciss —
—5.0
4.0 pF
Reverse Transfer Capacitance (ID = 1.0 mAdc, VDS = 10 Vdc, f = 1.0 MHz)
(ID = 200 Adc, VDS = 10 Vdc, f = 1.0 MHz) Crss —
—1.5
1.5 pF
TYPICAL CHARACTERISTICS
f, FREQUENCY (kHz)
Figure 1. Noise Figure versus Frequency
RS, SOURCE RESISTANCE (Megohms)
Figure 2. Noise Figure versus Source
Resistance
VDS, DRAIN-SOURCE VOLTAGE (VOLTS)
Figure 3. Typical Drain Characteristics
VGS, GATE-SOURCE VOLTAGE (VOLTS)
Figure 4. Common Source Transfer
Characteristics
14
0.01
4
3
2
0
1.0
0.4
0.2
0
12
1
0.1 1.0 10 100
5
10
8
6
4
2
-1.2
0.8
0.6
0 5 10 15 20 25
0
0.6
0.4
0.2
0.8
1.2
1.0
-0.8 -0.4 0
1.2
0
, DRAIN CURRENT (mA)
D
I
, DRAIN CURRENT (mA)
D
I
NF, NOISE FIGURE (dB)
NF, NOISE FIGURE (dB)
0.001 0.01 0.1 1.0 10
VDS = 15 V
VGS = 0
RS = 1 M
VDS = 15 V
VGS = 0
f = 1 kHz
VDS = 15 V
VGS = 0 V
-0.2 V
-0.4 V
-0.6 V
-0.8 V
-1.0 V
VGS(off) -1.2 V
VGS(off) -1.2 V
BFR30LT1 BFR31LT1
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TYPICAL CHARACTERISTICS
VDS, DRAIN-SOURCE VOLTAGE (VOLTS)
Figure 5. Typical Drain Characteristics
VGS, GATE-SOURCE VOLTAGE (VOLTS)
Figure 6. Common Source Transfer
Characteristics
VDS, DRAIN-SOURCE VOLTAGE (VOLTS)
Figure 7. Typical Drain Characteristics
VGS, GATE-SOURCE VOLTAGE (VOLTS)
Figure 8. Common Source Transfer
Characteristics
0
0
4
3
2
1
0
10
4
2
0
-4
5
510152025
5
4
3
2
1
0
-7
8
6
-6 -5 -4 -3 -2 -1
-5 -3 -2 -1 0
, DRAIN CURRENT (mA)
D
I
VDS = 15 V
VGS(off) -5.8 V
, DRAIN CURRENT (mA)
D
I
, DRAIN CURRENT (mA)
D
I, DRAIN CURRENT (mA)
D
I
VDS = 15 V
10
4
2
0
8
6
0 5 10 15 20 25
VGS(off) -5.8 V
VGS = 0 V
VGS = 0 V
-2 V
-1 V
-3 V
-1 V
-2 V
-3 V
-4 V
-5 V
VGS(off) -3.5 V
VGS(off) -3.5 V
Note: Graphical data is presented for dc conditions. Tabular
data is given for pulsed conditions (Pulse Width = 630
ms, Duty Cycle = 10%). Under dc conditions, self heat-
ing in higher IDSS units reduces IDSS.
