5
FN2921.12
October 18, 2013
Schematic Diagram
Application Information
Layout Considerations
The wide bandwidth of the HA-5002 necessitates that high
frequency circuit layout procedures be followed. Failure to
follow these guidelines can result in marginal performance.
Probably the most crucial of the RF/video layout rules is the
use of a ground plane. A ground plane provides isolation and
minimizes distributed circuit capacitance and inductance
which will degrade high frequency performance.
Other considerations are proper power supply bypassing
and keeping the input and output connections as short as
possible which minimizes distributed capacitance and
reduces board space.
Power Supply Decoupling
For optimal device performance, it is recommended that the
positive and negative power supplies be bypassed with
capacitors to ground. Ceramic capacitors ranging in value
from 0.01 to 0.1
μF will minimize high frequency variations in
supply voltage, while low frequency bypassing requires
larger valued capacitors since the impedance of the
capacitor is dependent on frequency.
It is also recommended that the bypass capacitors be
connected close to the HA-5002 (preferably directly to the
supply pins).
Operation at Reduced Supply Levels
The HA-5002 can operate at supply voltage levels as low as
±5V and lower. Output swing is directly affected as well as
slight reductions in slew rate and bandwidth.
Short Circuit Protection
The output current can be limited by using the following
circuit:
Capacitive Loading
The HA-5002 will drive large capacitive loads without oscillation
but peak current limits should not be exceeded. Following the
formula I = Cdv/dt implies that the slew rate or the capacitive
load must be controlled to keep peak current below the
maximum or use the current limiting approach as shown. The
HA-5002 can become unstable with small capacitive loads
(50pF) if certain precautions are not taken. Stability is
enhanced by any one of the following: a source resistance in
series with the input of 50
Ω to 1kΩ; increasing capacitive load
to 150pF or greater; decreasing CLOAD to 20pF or less; adding
an output resistor of 10
Ω to 50Ω; or adding feedback
capacitance of 50pF or greater. Adding source resistance
generally yields the best results.
R9
R10
Q25
Q9
Q10
R5
Q11
Q15
Q23
R7
Q21
Q22
Q24
Q27
Q26
R8
Q20
Q18
Q3
R4
R1
Q7
Q4
Q8
R6
R3
R12
Q16
Q14
Q13
R2
RN3
R11
Q5
Q6
Q12
RN1
Q19
RN2
V1-
V2-
OUT
V2+
V1+
Q1
Q2
IN
Q17
OUT
IN
V+
RLIM
V1-
V2-
V2+
V1+
V-
IOUTMAX = 200mA
(CONTINUOUS)
RLIM
V+
IOUTMAX
--------------------------
V-
IOUTMAX
--------------------------
==
HA-5002