el2004cg ETC-unknow, el2004cg Datasheet - Page 7

• Manufacturer Part Number: el2004cg
• Description: 350 Mhz Fet Buffer
• Manufacturer: ETC-unknow

Applications Information
The EL2004 is one member of a family of high
performance buffers manufactured by Elantec
The 2004 is optimized for speed while others offer
choices of input DC parameters or output drive
or cost The following table illustrates those
members available at the time of this printing
Consult the factory for the latest capabilities in
this developing line
Recommended Layout Precautions
The very high-speed performance of the EL2004
can only be realized by taking certain precau-
tions in circuit layout and power supply decou-
pling Low inductance ceramic chip or disc power
supply decoupling capacitors of 0 1
should be connected with the shortest practical
lead lengths between the device supply leads and
a ground plane In addition it can be helpful to
parallel these with 4 7
lum preferred) Failure to follow these precau-
tions can result in oscillation
Circuit Operation
The EL2004 is effectively an ideal unity gain am-
plifier with almost infinite input impedance and
about 6
Input Characteristics
The input impedance of a junction FET is a
strong function of temperature and input volt-
age Nominal input resistance of EL2004 is 10
at 25 C junction but as I
the JFET the input resistance falls During
warm-up self-heating raises the junction temper-
ature up to 60 C or more (without heatsink) so
operating I
sheet 25 C specification
Another factor which can increase bias current is
input voltage If the input voltage is more than
20V below the positive supply the input current
rises exponentially (See Curve )
ELH0002
ELH0033
EL2004
EL2005
Part
output impedance
Slew
Rate
V
1500
2500
1500
200
B
Elantec’s Buffer Family
will be much higher than the data
s
Bandwidth
MHz
100
350
140
50
B
F electrolytics (Tanta-
doubles every 11 C in
Current
(Warm)
Input
2 5 nA
2 5 nA
0 1 nA
6 A
Peak
I
mA
OUT
400
250
250
250
F or more
Time
Rise
2 9
1 0
2 5
ns
7
12
7
In applications such as sample and hold circuits
where it is important to maintain low input bias
current over input voltage range the EL2005
High Accuracy Fast Buffer is recommended
The input capacitance of EL2004 comprises the
FET device gate-to-source capacitance (which is
a function of input voltage) and stray capaci-
tance to the case Effective input capacitance can
be minimized by connecting the case to the out-
put since it is electrically isolated Or for reduced
radiation the case may be grounded The AC
characteristics specified in this data sheet were
obtained with the case floating
Offset Voltage Adjustment
The EL2004’s offset voltages have been actively
laser trimmed at
limits when the offset adjust pin is shorted to the
offset preset pin If external offset null is re-
quired the offset adjust pin should be connected
to a 200
ply
EL2004 EL2004C
trim pot connected to the negative sup-
350 MHz FET Buffer
Input Bias Current vs
Temperature
Input Bias Current vs
Input Voltage
g
15V supplies to meet specified
2004 – 9