JFET VHF/UHF Amplifiers
N–Channel — Depletion
MAXIMUM RATINGS
Rating Symbol Value Unit
Drain–Source Voltage VDS ±30 Vdc
Drain–Gate Voltage VDG 30 Vdc
Gate–Source Voltage VGS 30 Vdc
Drain Current ID100 mAdc
Forward Gate Current IG(f) 10 mAdc
Total Device Dissipation @ TA = 25°C
Derate above 25°CPD350
2.8 mW
mW/°C
Storage Channel Temperature Range Tstg –65 to +150 °C
3 DRAIN
1 SOURCE
2
GATE
3 DRAIN
2 SOURCE
1
GATE
STYLE 22 STYLE 23
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted)
Characteristic Symbol Min Typ Max Unit
OFF CHARACTERISTICS
Gate–Source Breakdown Voltage
(IG = 1.0 µAdc, VDS = 0) V(BR)GSS 30 — — Vdc
Gate–Source
(VDS = 15 Vdc, ID = 200 µAdc) BF245(1)
BF245A, BF244A(2)
BF245B, BF244B
BF245C
VGS 0.4
0.4
1.6
3.2
—
—
—
—
7.5
2.2
3.8
7.5
Vdc
Gate–Source Cutoff Voltage
(VDS = 15 Vdc, ID = 10 nAdc) VGS(off) –0.5 — –8.0 Vdc
Gate Reverse Current
(VGS = 20 Vdc, VDS = 0) IGSS — — 5.0 nAdc
ON CHARACTERISTICS
Zero–Gate–Voltage Drain Current
(VDS = 15 Vdc, VGS = 0) BF245(1)
BF245A, BF244A(2)
BF245B, BF244B
BF245C
IDSS 2.0
2.0
6.0
12
—
—
—
—
25
6.5
15
25
mAdc
1. On orders against the BF245, any or all subgroups might be shipped.
2. On orders against the BF244A, any or all subgroups might be shipped.
ON Semiconductor
Semiconductor Components Industries, LLC, 2001
June, 2001 – Rev. 0 332 Publication Order Number:
BF245A/D
BF245A
BF245B
BF244A, BF244B
CASE 29–11, STYLE 22
TO–92 (TO–226AA)
123
BF245, BF245A,
BF245B, BF245C
CASE 29–11, STYLE 23
TO–92 (TO–226AA)
123
BF245A BF245B
http://onsemi.com
333
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted) (Continued)
Characteristic Symbol Min Typ Max Unit
SMALL–SIGNAL CHARACTERISTICS
Forward Transfer Admittance (VDS = 15 Vdc, VGS = 0, f = 1.0 kHz) Yfs3.0 — 6.5 mmhos
Output Admittance (VDS = 15 Vdc, VGS = 0, f = 1.0 kHz) Yos— 40 — mhos
Forward Transfer Admittance (VDS = 15 Vdc, VGS = 0, f = 200 MHz) Yfs— 5.6 — mmhos
Reverse Transfer Admittance (VDS = 15 Vdc, VGS = 0, f = 200 MHz) Yrs— 1.0 — mmhos
Input Capacitance (VDS = 20 Vdc, –VGS = 1.0 Vdc) Ciss — 3.0 — pF
Reverse Transfer Capacitance (VDS = 20 Vdc, –VGS = 1.0 Vdc, f = 1.0 MHz) Crss — 0.7 — pF
Output Capacitance (VDS = 20 Vdc, –VGS = 1.0 Vdc, f = 1.0 MHz) Coss — 0.9 — pF
Cut–of f Frequency(3) (VDS = 15 Vdc, VGS = 0) F(Yfs) — 700 — MHz
3. The frequency at which gfs is 0.7 of its value at 1 kHz.
f, FREQUENCY (MHz)
30
10
bis @ IDSS
f, FREQUENCY (MHz)
5.0
Figure 1. Input Admittance (yis) Figure 2. Reverse Transfer Admittance (yrs)
COMMON SOURCE CHARACTERISTICS
ADMITTANCE PARAMETERS
(VDS = 15 Vdc, Tchannel = 25°C)
f, FREQUENCY (MHz)
20
f, FREQUENCY (MHz)
10
Figure 3. Forward Transadmittance (yfs) Figure 4. Output Admittance (yos)
gis, INPUT CONDUCTANCE (mmhos)
20
10
0.3
0.5
0.7
1.0
2.0
3.0
5.0
7.0
20 30 50 70 100 200 300 500 700 1000
bis, INPUT SUSCEPTANCE (mmhos)
gfs, FORWARD TRANSCONDUCTANCE (mmhos)
|bfs|, FORWARD SUSCEPTANCE (mmhos)
grs, REVERSE TRANSADMITTANCE (mmhos)
brs, REVERSE SUSCEPTANCE (mmhos)
0.2
0.3
0.5
0.7
1.0
2.0
3.0
5.0
7.0
10
gos, OUTPUT ADMITTANCE (mhos)
bos, OUTPUT SUSCEPTANCE (mhos)
3.0
0.05
0.07
0.1
0.2
0.3
0.7
0.5
1.0
2.0
10 20 30 50 70 100 200 300 500 700 1000
10 20 30 50 70 100 200 300 500 700 1000 0.01
0.02
0.05
0.1
0.2
0.5
1.0
2.0
5.0
10 20 30 50 70 100 200 300 500 7001000
bis @ 0.25 IDSS
gis @ IDSS
gis @ 0.25 IDSS
brs @ IDSS
0.25 IDSS
grs @ IDSS, 0.25 IDSS
gfs @ IDSS
|bfs| @ IDSS
|bfs| @ 0.25 IDSS
bos @ IDSS and 0.25 IDSS
gos @ IDSS
gos @ 0.25 IDSS
gfs @ 0.25 IDSS
BF245A BF245B
http://onsemi.com
334
Figure 5. S11s Figure 6. S12s
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
3
2
31
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
320°
310°
300°
290°
280°
270°
260°
250°
240°
230°
220°
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
3
2
31
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
320°
310°
300°
290°
280°
270°
260°
250°
240°
230°
220°
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
1.0
0.9
0.8
0.7
0.6
0.4
0.3
0.2
0.1
0.0
1.0
0.9
0.8
0.7
0.6
0.6
0.5
0.4
0.3
0.3
0.4
0.5
0.6
900 900
800
700
600
500
400
300
200
100
800
700
600
500
400
300
200
100
ID = 0.25 IDSS
ID = IDSS
100
200
300
400
600 700
800
900
500
ID = IDSS, 0.25 IDSS
900
500
800
700
600
500
400
300 200
100
ID = 0.25 IDSS
ID = IDSS 100
200
300
400
900
600
700
800
900
800
600
400
300
200
200
100 ID = 0.25 IDSS
ID = IDSS
900
100 500
700
300
400
500
600
700
800
Figure 7. S21s Figure 8. S22s
COMMON SOURCE CHARACTERISTICS
S–PARAMETERS
(VDS = 15 Vdc, Tchannel = 25°C, Data Points in MHz)
BF245A BF245B
http://onsemi.com
335
f, FREQUENCY (MHz)
10
gig @ IDSS
f, FREQUENCY (MHz)
0.5
Figure 9. Input Admittance (yig) Figure 10. Reverse Transfer Admittance (yrg)
COMMON GATE CHARACTERISTICS
ADMITTANCE PARAMETERS
(VDG = 15 Vdc, Tchannel = 25°C)
f, FREQUENCY (MHz) f, FREQUENCY (MHz)
Figure 11. Forward Transfer Admittance (yf
g
) Figure 12. Output Admittance (yo
g
)
gig, INPUT CONDUCTANCE (mmhos)
20
10
0.3
0.5
0.7
1.0
2.0
3.0
5.0
7.0
20 30 50 70 100 200 300 500 700 1000
big, INPUT SUSCEPTANCE (mmhos)
gfg, FORWARD TRANSCONDUCTANCE (mmhos)
bfg, FORWARD SUSCEPTANCE (mmhos)
grg, REVERSE TRANSADMITTANCE (mmhos)
brg, REVERSE SUSCEPTANCE (mmhos)
0.2
0.3
0.5
0.7
1.0
2.0
3.0
5.0
7.0
10
gog, OUTPUT ADMITTANCE (mmhos)
bog, OUTPUT SUSCEPTANCE (mmhos)
0.3
0.01
0.1
0.2
10 20 30 50 70 100 200 300 500 700 1000
10 20 30 50 70 100 200 300 500 700 1000 0.01
0.02
0.03
0.3
10 20 30 50 70 100 200 300 500 700 1000
big @ 0.25 IDSS
big @ IDSS
grg @ 0.25 IDSS
gfg @ IDSS
gfg @ 0.25 IDSS
brg @ 0.25 IDSS
bog @ IDSS, 0.25 IDSS
gog @ IDSS
gog @ 0.25 IDSS
0.2 0.005
0.007
0.02
0.03
0.05
0.07
0.1
0.05
0.07
0.1
0.2
0.5
0.7
1.0
brg @ IDSS
0.25 IDSS
gig @ IDSS, 0.25 IDSS
bfg @ IDSS
BF245A BF245B
http://onsemi.com
336
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
320°
310°
300°
290°
280°
270°
260°
250°
240°
230°
220°
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
3
2
31
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
320°
310°
300°
290°
280°
270°
260°
250°
240°
230°
220°
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
0°350°340°330°10°20°30°
180°190°200°210°170°160°150°
3
2
31
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
Figure 13. S11g Figure 14. S12g
Figure 15. S21
g
Figure 16. S22
g
0.7
0.6
0.5
0.4
0.3
0.04
0.5
0.4
0.3
0.2
1.0
0.9
0.8
0.7
0.6
0.03
0.02
0.01
0.0
0.01
0.02
0.03
0.04
0.1
900
900
800
700
600
500
300
200
100
800
700
600
500
400
300
200
100
ID = 0.25 IDSS
ID = IDSS
100 200 300 400
500
600
700
800
900
900
600
700
800
ID = 0.25 IDSS
ID = IDSS
100
900
100
900
ID = 0.25 IDSS
ID = IDSS
1.5
100 400
500
600 700
800 900
ID = IDSS, 0.25 IDSS
COMMON GATE CHARACTERISTICS
S–PARAMETERS
(VDS = 15 Vdc, Tchannel = 25°C, Data Points in MHz)
