ON Semiconductort
JFET VHF/UHF Amplifiers
N–Channel — Depletion
BF245A
BF245B
MAXIMUM RATINGS
Rating
Drain–Source Voltage
Drain–Gate Voltage
Gate–Source Voltage
Drain Current
Forward Gate Current
Total Device Dissipation @ T
A
= 25°C
Derate above 25°C
Storage Channel Temperature Range
3 DRAIN
Symbol
V
DS
V
DG
V
GS
I
D
I
G(f)
P
D
T
stg
Value
±30
30
30
100
10
350
2.8
–65 to +150
3 DRAIN
Unit
Vdc
Vdc
Vdc
mAdc
mAdc
mW
mW/°C
°C
1
2
3
BF244A, BF244B
CASE 29–11, STYLE 22
TO–92 (TO–226AA)
1
2
3
2
GATE
STYLE 22
1
GATE
STYLE 23
BF245, BF245A,
BF245B, BF245C
CASE 29–11, STYLE 23
TO–92 (TO–226AA)
2 SOURCE
1 SOURCE
ELECTRICAL CHARACTERISTICS
(T
A
= 25°C unless otherwise noted)
Characteristic
Symbol
Min
Typ
Max
Unit
OFF CHARACTERISTICS
Gate–Source Breakdown Voltage
(I
G
= 1.0
µAdc,
V
DS
= 0)
Gate–Source
(V
DS
= 15 Vdc, I
D
= 200
µAdc)
BF245
(1)
BF245A,
BF245B,
BF245C
V
(BR)GSS
V
GS
BF244A
(2)
BF244B
V
GS(off)
I
GSS
0.4
0.4
1.6
3.2
–0.5
—
—
—
—
—
—
—
7.5
2.2
3.8
7.5
–8.0
5.0
Vdc
nAdc
30
—
—
Vdc
Vdc
Gate–Source Cutoff Voltage
(V
DS
= 15 Vdc, I
D
= 10 nAdc)
Gate Reverse Current
(V
GS
= 20 Vdc, V
DS
= 0)
ON CHARACTERISTICS
Zero–Gate–Voltage Drain Current
(V
DS
= 15 Vdc, V
GS
= 0)
BF245
(1)
BF245A,
BF245B,
BF245C
BF244A
(2)
BF244B
I
DSS
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.
©
Semiconductor Components Industries, LLC, 2001
332
June, 2001 – Rev. 0
Publication Order Number:
BF245A/D
BF245A BF245B
ELECTRICAL CHARACTERISTICS
(T
A
= 25°C unless otherwise noted) (Continued)
Characteristic
Symbol
Min
Typ
Max
Unit
SMALL–SIGNAL CHARACTERISTICS
Forward Transfer Admittance
Output Admittance
Forward Transfer Admittance
Reverse Transfer Admittance
Input Capacitance
Reverse Transfer Capacitance
Output Capacitance
Cut–off Frequency
(3)
3. The frequency at which g
fs
is 0.7 of its value at 1 kHz.
(V
DS
= 15 Vdc, V
GS
= 0, f = 1.0 kHz)
(V
DS
= 15 Vdc, V
GS
= 0, f = 1.0 kHz)
(V
DS
= 15 Vdc, V
GS
= 0, f = 200 MHz)
(V
DS
= 15 Vdc, V
GS
= 0, f = 200 MHz)
(V
DS
= 20 Vdc, –V
GS
= 1.0 Vdc)
(V
DS
= 20 Vdc, –V
GS
= 1.0 Vdc, f = 1.0 MHz)
(V
DS
= 20 Vdc, –V
GS
= 1.0 Vdc, f = 1.0 MHz)
(V
DS
= 15 Vdc, V
GS
= 0)
Y
fs
Y
os
Y
fs
Y
rs
C
iss
C
rss
C
oss
F
(Yfs)
3.0
—
—
—
—
—
—
—
—
40
5.6
1.0
3.0
0.7
0.9
700
6.5
—
—
—
—
—
—
—
mmhos
mmhos
mmhos
mmhos
pF
pF
pF
MHz
COMMON SOURCE CHARACTERISTICS
ADMITTANCE PARAMETERS
(V
DS
= 15 Vdc, T
channel
= 25°C)
grs , REVERSE TRANSADMITTANCE (mmhos)
brs , REVERSE SUSCEPTANCE (mmhos)
30
20
10
7.0
5.0
3.0
2.0
1.0
0.7
0.5
0.3
10
20
30
b
is
@ I
DSS
5.0
3.0
2.0
1.0
0.7
0.5
0.3
0.2
g
rs
@ I
DSS
, 0.25 I
DSS
10
20
30
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
b
rs
@ I
DSS
0.25 I
DSS
gis, INPUT CONDUCTANCE (mmhos)
bis, INPUT SUSCEPTANCE (mmhos)
g
is
@ I
DSS
g
is
@ 0.25 I
DSS
b
is
@ 0.25 I
DSS
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
0.1
0.07
0.05
Figure 1. Input Admittance (y
is
)
Figure 2. Reverse Transfer Admittance (y
rs
)
gfs, FORWARD TRANSCONDUCTANCE (mmhos)
|b fs|, FORWARD SUSCEPTANCE (mmhos)
20
10
7.0
5.0
3.0
2.0
1.0
0.7
0.5
0.3
0.2
10
|b
fs
| @ I
DSS
|b
fs
| @ 0.25 I
DSS
gos, OUTPUT ADMITTANCE (mhos)
bos, OUTPUT SUSCEPTANCE (mhos)
10
5.0
2.0
1.0
0.5
0.2
0.1
g
os
@ I
DSS
b
os
@ I
DSS
and 0.25 I
DSS
g
fs
@ I
DSS
g
fs
@ 0.25 I
DSS
0.05
0.02
0.01
10
20
30
g
os
@ 0.25 I
DSS
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
20
30
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
Figure 3. Forward Transadmittance (y
fs
)
Figure 4. Output Admittance (y
os
)
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333
BF245A BF245B
COMMON SOURCE CHARACTERISTICS
S–PARAMETERS
(V
DS
= 15 Vdc, T
channel
= 25°C, Data Points in MHz)
30°
40°
20°
10°
0°
1.0
350°
100
100
50°
0.9
200
300
60°
70°
80°
90°
100°
110°
120°
0.8
I
D
= I
DSS
400
500
600
0.6
900
800
700
900
600
700
800
290°
280°
270°
260°
250°
240°
70°
80°
90°
100°
110°
120°
340°
330°
320°
40°
30°
20°
10°
0°
0.4
350°
340°
330°
32
I
D
= 0.25 I
DSS
200
300
400
500
300°
60°
310°
50°
I
D
= I
DSS
, 0.25 I
DSS
800
600
400
300
200
100
0.0
700
500
0.1
900
0.2
30
29
28
27
26
25
24
0.3
31
0.7
130°
230°
130°
23
140°
150°
160°
170°
180°
190°
200°
210°
220°
140°
150°
160°
170°
180°
190°
200°
210°
22
Figure 5. S
11s
30°
40°
20°
10°
0°
350°
340°
330°
320°
40°
30°
20°
Figure 6. S
12s
10°
0°
350°
340°
330°
100 200
I
D
= 0.25 I
DSS
300
1.0
400
100 200
500
300
600
400
700
0.9
500
800
600
I
D
= I
DSS
700
900
800
900
0.8
32
50°
0.6
310°
50°
31
60°
70°
80°
90°
100°
110°
120°
900
800
700
600
500
400
300
I
D
= I
DSS
200
100
800
700
600
I
D
= 0.25 I
DSS
500
400
300
200
100
900
0.5
300°
290°
280°
270°
60°
70°
80°
90°
100°
110°
120°
30
29
28
27
26
25
24
0.4
0.7
0.3
0.6
0.3
260°
250°
240°
0.4
0.5
130°
0.6
230°
130°
23
140°
150°
160°
170°
180°
190°
200°
210°
220°
140°
150°
160°
170°
180°
190°
200°
210°
22
Figure 7. S
21s
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334
Figure 8. S
22s
BF245A BF245B
COMMON GATE CHARACTERISTICS
ADMITTANCE PARAMETERS
(V
DG
= 15 Vdc, T
channel
= 25°C)
grg , REVERSE TRANSADMITTANCE (mmhos)
brg , REVERSE SUSCEPTANCE (mmhos)
20
gig, INPUT CONDUCTANCE (mmhos)
big, INPUT SUSCEPTANCE (mmhos)
10
7.0
5.0
3.0
2.0
1.0
0.7
0.5
0.3
0.2
10
20
30
0.5
0.3
0.2
0.1
0.07
0.05
0.03
0.02
0.01
10
20
30
g
ig
@ I
DSS
, 0.25 I
DSS
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
0.25 I
DSS
b
rg
@ I
DSS
g
ig
@ I
DSS
g
rg
@ 0.25 I
DSS
b
ig
@ I
DSS
b
ig
@ 0.25 I
DSS
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
0.007
0.005
Figure 9. Input Admittance (y
ig
)
Figure 10. Reverse Transfer Admittance (y
rg
)
gfg , FORWARD TRANSCONDUCTANCE (mmhos)
bfg , FORWARD SUSCEPTANCE (mmhos)
3.0
2.0
1.0
0.7
0.5
0.3
0.2
0.1
10
20
30
b
fg
@ I
DSS
g
fg
@ 0.25 I
DSS
gog, OUTPUT ADMITTANCE (mmhos)
bog, OUTPUT SUSCEPTANCE (mmhos)
10
7.0
5.0
g
fg
@ I
DSS
1.0
0.7
0.5
0.3
0.2
0.1
0.07
0.05
0.03
0.02
0.01
10
b
og
@ I
DSS
, 0.25 I
DSS
g
og
@ I
DSS
b
rg
@ 0.25 I
DSS
50 70 100
200 300
f, FREQUENCY (MHz)
g
og
@ 0.25 I
DSS
20
30
50 70 100
200 300
f, FREQUENCY (MHz)
500 700 1000
500 700 1000
Figure 11. Forward Transfer Admittance (y
fg
)
Figure 12. Output Admittance (y
og
)
http://onsemi.com
335
BF245A BF245B
COMMON GATE CHARACTERISTICS
S–PARAMETERS
(V
DS
= 15 Vdc, T
channel
= 25°C, Data Points in MHz)
30°
40°
20°
10°
0°
0.7
100
0.6
50°
100
0.5
60°
70°
80°
90°
100°
110°
120°
0.4
I
D
= I
DSS
200
200
300
350°
340°
330°
320°
40°
30°
20°
10°
0°
0.04
350°
340°
330°
32
I
D
= 0.25 I
DSS
400
0.03
500
600
700
800
900
290°
280°
270°
260°
250°
240°
70°
80°
90°
100°
110°
120°
600
I
D
= I
DSS
700
800
900
100
500
600
700
800
I
D
= 0.25 I
DSS
0.01
0.01
29
28
27
26
25
24
310°
50°
0.02
31
300
400
500
600
700
300°
60°
30
0.3
800
900
0.0
0.02
130°
230°
130°
900
23
0.03
22
190°
200°
210°
140°
150°
160°
170°
180°
190°
200°
210°
220°
140°
150°
160°
170°
0.04
180°
Figure 13. S
11g
30°
40°
20°
10°
0°
0.5
100
100
0.3
I
D
= I
DSS
310°
50°
350°
340°
330°
320°
40°
30°
20°
Figure 14. S
12g
10°
0°
1.5
1.0
100
0.9
350°
300
200
400
340°
500
600
700
800
900
31
330°
32
0.4
50°
I
D
= I
DSS
, 0.25 I
DSS
0.8
60°
70°
80°
90°
100°
110°
120°
300°
I
D
= 0.25 I
DSS
290°
280°
900
900
270°
260°
250°
240°
60°
70°
80°
90°
100°
110°
120°
30
29
28
27
26
25
24
0.2
0.7
0.1
0.6
130°
230°
130°
23
140°
150°
160°
170°
180°
190°
200°
210°
220°
140°
150°
160°
170°
180°
190°
200°
210°
22
Figure 15. S
21g
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336
Figure 16. S
22g
嵌入式系统
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