LMH730227/LMH730216/LMH730165
Single High Speed Op Amp Evaluation Boards (SOIC,
SOT23, and SC70)
The LMH730227, LMH730216 and LMH730165 evaluation
boards are designed to aid in the characterization of National
Semiconductor’s High Speed monolithic amplifiers.
•LMH730227 — SOIC packages
•LMH730216 — SOT23 packages
•LMH730165 — SC70 packges
Use the evaluation boards as a guide for high frequency
layout and as a tool to aid in device testing and character-
ization.
The evaluation boards accommodate general purpose am-
plifiers, as well as amplifiers with the following features:
•Supply current adjustment via external Resistor
•Output disable
The evaluation board schematic is shown below. Refer to the
product data sheets for recommendations for component
values.
BASIC OPERATION
These boards have identical circuit configurations and are
designed to accommodate both non-inverting and inverting
operation. By changing RT or RIN and ROUT different input
and output impedances can be matched. The SMA connec-
tors and board traces are optimized for 50Ωoperation, how-
ever other impedances can be matched as shown below.
Inverting Gain = R
F
/R
G
(Input Resistance = R
T
|| R
G
)
Non Inverting Gain=1+R
F
/(R
G
+R
T
)
(Input Resistance = R
IN
)
(R
T
may be set to zero for non inverting operation)
For current feedback operational amplifiers be careful to use
appropriate values of R
F
. In addition the required value of R
G
will limit choices for input impedance with Inverting gains.
20066601
FIGURE 1. SOT and SC70 Schematic
June 2006
LMH730227/LMH730216/ LMH730165 Single High Speed Op Amp Evaluation Boards (SOIC,
SOT23 and SC70)
© 2006 National Semiconductor Corporation MS200666 www.national.com
(Continued)
LAYOUT CONSIDERATIONS
Printed circuit board layout and supply bypassing play major
roles in determining high frequency performance. When de-
signing your own board use these evaluation boards as a
guide and follow these steps to optimize high frequency
performance:
20066602
FIGURE 2. SOIC Schematic
20066603
FIGURE 3. Probe Schematic
LMH730227,LMH730216
www.national.com 2
(Continued)
1. Use a ground plane
2. Include large (~6.8µF) capacitors on both supplies.
3. Near the device use .01µF ceramic capacitors from both
supplies to ground C
1
,C
3
.
4. Near the device use a .1µF ceramic capacitor between
the supplies C
5
.
5. Remove the ground and power planes from under and
around the part, especially the input and output pins.
6. Minimize all trace lengths
7. Use terminated transmission lines for long traces.
8. High-speed disable/enable operation requires that the
enable pin be treated as a signal input.
Diode D
1
is to protect the device from reverse polarity supply
connections and will not be necessary for most designs.
Capacitor C
5
is necessary for best Harmonic Distortion per-
formance. If C
5
is not used increase the values of C
1
and C
3
to .1µF.
R
IN
,R
T
and R
OUT
are all impedance matching resistors. R
IN
and R
OUT
should be equal to the desired input/output imped-
ance. R
T
|| R
G
should equal the desired inverting input
impedance. Note that with current feedback op amps, the
optimum value of R
F
and R
G
is determined by the desired
gain and raising R
G
to obtain higher input impedance may
require compromising device performance at large values of
inverting gain.
The disable trace has provisions for input termination. There
are also pads for series resistance and capacitance for
programmable gain parts. See part datasheets for sug-
gested values.
Sample artwork for National’s Evaluation boards is included
below.
The board is designed for 50Ωinput and output connections
into coaxial cables. For other impedances the terminating
resistors can be modified to help match different imped-
ances.
Do not use normal oscilloscope probes to test these circuits.
The capacitive loading will change circuit performance dras-
tically. Instead use low impedance resistive divider probes of
100 to 500Ω. See Figure 3 for a sample resistive probe. The
Low impedance resistor should be 50-450Ω. The ground
connection should be as short as possible (~1/2"). Even with
careful use of these probes results should be considered
preliminary until verified with controlled impedance measure-
ments. Even the best probes will interfere with circuit opera-
tion to some degree. Also, conductors, fingers etc. near the
device will change measurement results.
National Semiconductor Layer1 Silk National Semiconductor Layer1 Silk
20066604 20066605
SOIC Board Layout (Actual size = 1.5" x 1.5"). The boards may be marked as CLC730227 or LMH730227
LMH730227,LMH730216
www.national.com3
(Continued)
National Semiconductor Layer1 Silk National Semiconductor Layer1 Silk
20066606 20066607
SOT Board Layout (Actual size = 1.5" x 1.5"). The boards may be marked as CLC730216 or LMH730216
National Semiconductor Layer1 Silk National Semiconductor Layer1 Silk
20066608 20066609
SC70 Board Layout (Actual size = 1.5" x 1.5")
LMH730227,LMH730216
www.national.com 4
Notes
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support device
or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C2) and Banned Substances
and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at:
www.national.com/quality/green.
Lead free products are RoHS compliant.
National Semiconductor
Americas Customer
Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Support Center
Email: ap.support@nsc.com
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LMH730227/LMH730216/ LMH730165 Single High Speed Op Amp Evaluation Boards (SOIC,
SOT23 and SC70)
