
EL5170, EL5370
10
FN7309.9
August 28, 2012
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high frequency device, a good printed circuit board
layout is necessary for optimum performance. Lead lengths
should be as sort as possible. The power supply pin must be well
bypassed to reduce the risk of oscillation. For normal single
supply operation, where the VS- pin is connected to the ground
plane, a single 4.7F tantalum capacitor in parallel with a 0.1F
ceramic capacitor from VS+ to GND will suffice. This same
capacitor combination should be placed at each supply pin to
ground if split supplies are to be used. In this case, the VS- pin
becomes the negative supply rail.
For good AC performance, parasitic capacitance should be kept
to minimum. Use of wire wound resistors should be avoided
because of their additional series inductance. Use of sockets
should also be avoided if possible. Sockets add parasitic
inductance and capacitance that can result in compromised
performance. Minimizing parasitic capacitance at the amplifier’s
inverting input pin is very important. The feedback resistor
should be placed very close to the inverting input pin. Strip line
design techniques are recommended for the signal traces.
Typical Applications
0
Ω
VFB
VINB
VREF
EL5172/
EL5372
EL5170/
EL5370
VOUT
50
ZO = 100Ω
VIN
50
Ω
50
Ω
FIGURE 20. TWISTED PAIR DRIVER
IN+
IN-
FIGURE 21. DUAL COAXIAL CABLE DRIVER
IN-
0
Ω
VFB
VINB
VREF
VOUT
VIN
EL5172/EL5372
+
VIN
VREF
VIN
50
Ω
50
Ω
VOUTB
EL5170/EL5370
-
50
Ω COAX
50
Ω COAX
50
Ω
50
Ω
VOUT
IN+
EL5170/EL5370
IN+
IN-
VIN
10V
FIGURE 22. SINGLE SUPPLY TWISTED PAIR DRIVER
50
Ω
50
Ω
VREF
10k
ZO = 100Ω
TWISTED PAIR
100
Ω VOUT
TWISTED PAIR