User’s Guide
March 1999
Mixed-Signal Products
SLOU021A
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Preface
Related Documentation From Texas Instruments
THS3001 HIGH-SPEED CURRENT-FEEDBACK OPERATIONAL
AMPLIFIER (literature number SLOS217) This is the data sheet
for the THS3001 operational amplifier integrated circuit that is
used in the THS3001 evaluation module.
FCC Warning
This equipment is intended for use in a laboratory test environment only. It
generates, uses, and can radiate radio frequency energy and has not been
tested for compliance with the limits of computing devices pursuant to subpart
J of part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other
environments may cause interference with radio communications, in which
case the user at his own expense will be required to take whatever measures
may be required to correct this interference.
Trademarks
TI is a trademark of Texas Instruments Incorporated.
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Contents
1
2
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1
1.2
1.3
1.4
1.5
1.6
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
THS3001 EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Using The THS3001 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
THS3001 EVM Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
General High-Speed Amplifier Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1
2.2
2.3
2.4
THS3001 High-Speed Operational Amplifier EVM Parts List . . . . . . . . . . . . . . . . . . . . . . 2-2
THS3001 EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
THS3001 Rev. A High-Speed Operational Amplifier EVM Parts List . . . . . . . . . . . . . . . 2-4
THS3001 Rev. A. EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Figures
1–1
1–2
1–3
1–4
1–5
1–6
2–1
2–2
2–3
2–4
2–5
2–6
THS3001 Evaluation Module – Original Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
THS3001 Rev. A Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
THS3001 EVM Schematic – Original Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
THS3001 Rev. A EVM Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
THS3001 EVM Frequency Response with Gain = 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
THS3001 EVM Frequency Response with Inverting Gain = 1 . . . . . . . . . . . . . . . . . . . . . . . 1-7
THS3001 EVM Component Placement Silkscreen and Solder Pads . . . . . . . . . . . . . . . . . 2-2
THS3001 EVM PC Board Layout – Component Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
THS3001 EVM PC Board Layout – Back Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
THS3001 Rev. A EVM Component Placement Silkscreen and Solder Pads . . . . . . . . . . . 2-4
THS3001 Rev. A EVM PC Board Layout – Component Side . . . . . . . . . . . . . . . . . . . . . . . . 2-5
THS3001 Rev. A EVM PC Board Layout – Back Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Tables
2–1
2–2
THS3001 EVM Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
THS3001 Rev. A EVM Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
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Chapter 1
General Information
This chapter details the Texas Instruments (TI ) THS3001 high-speed
operational amplifier evaluation module (EVM), SLOP130. It includes a list of
EVM features, a brief description of the module illustrated with a pictorial and
a schematic diagram, EVM specifications, details on connecting and using the
EVM, and a discussion on high-speed amplifier design considerations.
Topic
Page
1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2
1.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2
1.3 THS3001 EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–5
1.4 Using The THS3001 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–6
1.5 THS3001 EVM Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7
1.6 General High-Speed Amplifier Design Considerations . . . . . . . . . . . 1–8
1-1
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Features
1.1 Features
THS3001 operational amplifier EVM features include:
High Bandwidth — 340 MHz, –3 dB at ±15 V
±5-V to ±15-V Operation
& Gain = 2
CC
Inverting and Noninverting Single-Ended Inputs
Module Gain Set to +2 (Noninverting) and –1 (Inverting) — Adjustable
Through Component Change.
Nominal 50-Ω Impedance Inputs and Outputs
Standard SMA Miniature RF Connectors
Good Example of High-Speed Amplifier Design and Layout
1.2 Description
The TI THS3001 high-speed current-feedback operational amplifier
evaluation module (EVM) is a complete high-speed amplifier circuit. It consists
of the TI THS3001 high-speed current-feedback operational amplifier IC,
along with a small number of passive parts, mounted on a small circuit board
measuring approximately 1.7 inch by 1.4 inch. The EVM uses standard SMA
miniature RF connectors for inputs and outputs and is completely assembled,
fully tested, and ready to use — just connect it to power, a signal source, and
a load (if desired).
Two versions of the THS3001 EVM are available. The original appears in
Figure 1–1 and the Rev. A version appears in Figure 1–2.
Figure 1–1. THS3001 Evaluation Module – Original Version
–VCC
+VCC
GND
J3
C3
–IN
+
+
C1
R5
GND
R1
C4
INVERTING
C2
U1
J2
R4
NONINVERTING
R2
R3
+IN
GND
J1
LITERATURE NO
SLOP 130
009957
THS3001 EVM
1-2
General Information
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Description
Figure 1–2. THS3001 Rev. A Evaluation Module
J1
–VCC
+VCC
C2
J2
C1
GND
+
–IN
+
GND
TEXAS
INSTRUMENTS
R2
INVERTING
Rev. A
J4
R4
C3
NONINVERTING
R1
R3
+IN
GND
R5
U1
C4
J3
SLOP130 Rev A
THS3001 EVM Board
The THS3001 EVM is equipped with both noninverting and inverting inputs.
The noninverting input is set for a gain of 2 and the inverting input is set for a
gain of 1. Each input is terminated with a 50-Ω resistor to provide correct line
impedance matching (Figure 1–3 for original version and Figure 1–4 for Rev.
A). The amplifier IC output is routed through a 50-Ω resistor both to provide
correct line impedance matching and to help isolate capacitive loading on the
output of the amplifier. Capacitive loading directly on the output of the IC
decreases the amplifier’s phase margin and can result in peaking or
oscillations.
Figure 1–3. THS3001 EVM Schematic – Original Version
V
CC
C2
+
0.1 µF
C1
R1
6.8 µF/35 V
1 kΩ
J1
J3
Non-
Inverting
Input
7
3
+
J2
R2
R3
49.9 Ω
6
U1
Output
THS3001
49.9 Ω
2
–
4
R5
1 kΩ
Inverting
Input
C3
6.8 µF/35 V
R4
C4
0.1 µF
+
49.9 Ω
–V
CC
1-3
General Information
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Description
Figure 1–4. THS3001 Rev. A EVM Schematic
V
CC
C2
6.8 µF
J1
1
–V
–V
CC
+
CC
2
3
GND
C3
0.1 µF
V
V
CC
CC
R2
R4
J2
1 kΩ 1 kΩ
–IN
Inverting
R1
49.9 Ω
7
2
–
R5
49.9 Ω
J4
6
U1
THS3001
Rev. A
Out
J3
3
+IN
Noninverting
+
4
C4
0.1 µF
R3
49.9 Ω
C1
6.8 µF
+
–V
CC
Even though the THS3001 is a current-feedback amplifier, the gain of the EVM
can easily be changed to support a particular application by simply changing
the ratio of resistors R1, R4, and R5 (R1, R2, and R4 for Rev. A) as described
in the following equations:
RF
RG
R1
R5
R4
R2
Inverting Gain
(Rev. A)
RF
RG
R1
R4 R5
R4
R2 R1
Noninverting Gain
1
1
1
(Rev. A)
In addition, some applications, such as those for video, may require the use
of 75-Ω cable and 75-Ω EVM input termination and output isolation resistors.
Any of the resistors on the EVM board can be replaced with a resistor of a
different value; however, care must be taken because the surface-mount
solder pads on the board are somewhat fragile and will not survive many
desoldering/soldering operations.
Because of the current feedback architecture, extra care must be taken to
ensure that a feedback resistor is always included in the design. In addition,
there must never be a capacitor directly in the feedback path between the
amplifier output and the noninverting input. Disregarding this guideline will
likely result in a part that oscillates.
1-4
General Information
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THS3001 EVM Specifications
Note: External factors can significantly affect the overall gain of the EVM. For
example, connecting test equipment with 50-Ω input impedance to the EVM
output will divide the output signal level by a factor of 2 (assuming the output
isolation resistor on the EVM board remains 50 Ω). Similar effects can occur
at the input, depending upon how the input signal sources are configured. The
gain equations given above assume no signal loss in either the input or the
output.
The EVM circuit board is an excellent example of proper board layout for
high-speed amplifier designs and can be used as a guide for user application
board layouts.
1.3 THS3001 EVM Specifications
Supply voltage range, ±V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5 V to ±15 V
CC
Supply current, I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 mA Typ
CC
Input voltage, V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±VCC, Max
I
Output drive, I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mA, Typ
O
Continuous power dissipation at T = 25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 740 mW
A
For complete THS3001 amplifier IC specifications and parameter
measurement information, and additional application information, see the
THS3001 data sheet, TI Literature Number SLOS217.
1-5
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Using The THS3001 EVM
1.4 Using The THS3001 EVM
The THS3001 EVM operates from power-supply voltages ranging from ±5 V
to ±15 V. As shipped, the inverting input gain of the module is set to 1, the
noninverting input gain is set to 2, and signal inputs on the module are
terminated for 50-Ω nominal impedance cables. An oscilloscope is typically
used to view and analyze the EVM output signal.
1.4.1 Steps for THS3001 EVM
1) Ensure that all power supplies are set toOFF before making power supply
connections to the THS3001 EVM.
2) Select the operating voltage for the EVM and connect appropriate split
power supplies to the pads on the module marked –VCC and +VCC.
3) Connect the power supply ground to the module pad marked GND.
4) Connect an oscilloscope to the module SMA output connector (J2)
through a 50-Ω nominal impedance cable (an oscilloscope having a 50-Ω
input termination is preferred for examining very high frequency signals).
5) Set the power supply to ON.
6) Connect the signal input to either the noninverting input (J1) for a gain of
2, or to the inverting input (J3) for a gain of 1.
1.4.2 Steps for THS3001 Rev. A EVM
1) Ensure that all power supplies are set toOFF before making power supply
connections to the THS3001 EVM.
2) Select the operating voltage for the EVM and connect appropriate split
power supplies to J1 terminals on the module marked –VCC and +VCC.
3) Connect the power supply ground to J1 terminal marked GND.
4) Connect an oscilloscope to the module SMA output connector (J4)
through a 50-Ω nominal impedance cable (an oscilloscope having a 50-Ω
input termination is preferred for examining very high frequency signals).
5) Set the power supply to ON.
6) Connect the signal input to either the noninverting input (J3) for a gain of
2, or to the inverting input (J2) for a gain of 1.
Note that each input connector is terminated with a 50-Ω resistor to ground.
With a 50-Ω source impedance, the voltage seen by the THS3001 amplifier
IC on the module will be the source signal voltage applied to the EVM.
7) Verify the output signal on the oscilloscope.
Note: The signal shown on an oscilloscope with a 50-Ω input impedance will
be the actual THS3001 amplifier IC output voltage. This is due to the voltage
division between the output resistor (R2) and the oscilloscope input
impedance.
1-6
General Information
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THS3001 EVM Performance
1.5 THS3001 EVM Performance
Figure 1–5 shows the typical frequency response of the THS3001 EVM using
the noninverting input (G = 2). Typical values show a –3-dB bandwidth of
340 MHz with a ±15-V power supply and 260 MHz with a ±5-V power supply.
They also show a –0.1-dB frequency response of 17 MHz with a ±15-V power
supply and 20 MHz with a ±5-V power supply.
Figure 1–5. THS3001 EVM Frequency Response with Gain = 2
7
6
V
CC
= ±15 V
5
4
3
V
CC
= ±5 V
2
1
0
–1
–2
–3
V = 200 mV RMS
I
R
= 150 Ω
load
100K
1M
10M
f – Frequency – Hz
100M
1G
Figure 1–6 shows the typical frequency response of the THS3001 EVM using
the inverting input (G = 1). Typical –0.1 dB bandwidths are 15 MHz with a
±15-V power supply and 17 MHz with a ±5-V power supply. Typical –3-dB
bandwidths are 220 MHz at ±15-V and 210 MHz at ±5-V.
Figure 1–6. THS3001 EVM Frequency Response with Inverting Gain = 1
1
0
V
CC
= ±15 V
–1
–2
–3
–4
–5
V
CC
= ±5 V
–6
–7
–8
–9
V = 200 mV RMS
I
R
= 150 Ω
load
100K
1M
10M
f – Frequency – Hz
100M
1G
1-7
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General High-Speed Amplifier Design Considerations
1.6 General High-Speed Amplifier Design Considerations
The THS3001 EVM layout has been designed and optimized for use with
high-speed signals and can be used as an example when designing THS3001
applications. Careful attention has been given to component selection,
grounding, powersupplybypassing, andsignalpathlayout. Disregardofthese
basic design considerations could result in less than optimum performance of
the THS3001 high-speed, current-feedback video operational amplifier.
Surface-mount components were selected because of the extremely low lead
inductance associated with this technology. Also, because surface-mount
components are physically small, the layout can be very compact. This helps
minimize both stray inductance and capacitance.
Tantalum power supply bypass capacitors (C1 and C3 for original and C1 and
C2 for Rev. A) at the power input pads help supply currents for rapid, large
signal changes at the amplifier output. The 0.1 µF power supply bypass
capacitors (C2 and C4 for original version and C3 and C4 for Rev. A) were
placed as close as possible to the IC power input pins in order to keep the PCB
trace inductance to a minimum. This improves high-frequency bypassing and
reduces harmonic distortion.
A proper ground plane on both sides of the PCB should always be used with
high-speed circuit design. This provides low-inductive ground connections for
return current paths. In the area of the amplifier IC input pins, however, the
ground plane was removed to minimize stray capacitance and reduce ground
plane noise coupling into these pins. This is especially important for the
invertingpinwhiletheamplifierisoperatinginthenoninvertingmode. Because
the voltage at this pin swings directly with the noninverting input voltage, any
stray capacitance would allow currents to flow into the ground plane, causing
possible gain error and/or oscillation. Capacitance variations at the amplifier
IC inverting input pin of less than 1 pF can significantly affect the response of
the amplifier.
In general, it is always best to keep signal lines as short and as straight as
possible. Sharp 90 corners should be avoided — round corners or a series
of 45 bends should be used, instead. Stripline techniques should also be
incorporated when signal lines are greater than three inches in length. These
traces should be designed with a characteristic impedance of either 50 Ω or
75 Ω, as required by the application. Such signal lines should also be properly
terminated with an appropriate resistor.
Finally, proper termination of all inputs and outputs should be incorporated into
the layout. Unterminated lines, such as coaxial cable, can appear to be a
reactive load to the amplifier IC. By terminating a transmission line with its
characteristic impedance, the amplifier’s load then appears to be purely
resistive and reflections are absorbed at each end of the line. Another
advantage of using an output termination resistor is that capacitive loads are
isolated from the amplifier output. This isolation helps minimize the reduction
in amplifier phase-margin and improves the amplifier stability for improved
performance such as reduced peaking and settling times.
1-8
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Chapter 2
Reference
This chapter includes a parts list and PCB layout illustrations for the THS3001
EVM and the THS3001 Rev. A EVM.
Topic
Page
2.1 THS3001 High-Speed Operational Amplifier EVM Parts List . . . . . . . 2–2
2.2 THS3001 EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–2
2.3 THS3001 Rev. A High-Speed Operational Amplifier EVM Parts List 2–4
2.4 THS3001 Rev. A EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–4
2-1
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THS3001 High-Speed Current-Feedback Video Operational Amplifier EVM Parts List
2.1 THS3001 High-Speed Current-Feedback Video Operational Amplifier
EVM Parts List
Table 2–1.THS3001 EVM Parts List
Manufacturer/Digi-Key
Reference
Description
Size
Part Number
C1, C3
Capacitor, 6.8 µF, 35 V, SM
D
Sprague 293D685X9035D2T
C2, C4
Capacitor, 0.1 µF, ceramic, 10%, SM
1206 Sprague 11C1201E104M5NT
Amphenol ARF1205–ND
J1, J2, J3
Connector, SMA 50-Ω vertical PC mount, through-
hole
R2, R3, R4 Resistor, 49.9 Ω, 1%, 1/10 W, SM
1206 Digi-Key P49.9CTR–ND
1206 Digi-Key P1.0KCTR–ND
SOIC-8 TI THS3001
R1, R5
U1
Resistor, 1 kΩ, 1%, 1/10 W, SM
IC, THS3001, operational amplifier
PCB, THS3001 EVM
PCB1
2.2 THS3001 EVM Board Layouts
Board layout examples of the THS3001 EVM PCB are shown in the following
illustrations. They are not to scale and appear here only as a reference.
Figure 2–1. THS3001 EVM Component Placement Silkscreen and Solder Pads
–VCC
J3
+VCC
GND
C3
–IN
R5
U1
C1
C2
GND
R1
C4
INVERTING
J2
NONINVERTING
R4
R3
R2
+IN
GND
LITERATURE NO.
SLOP 130
–3
009957
J1
THS3001 EVM
2-2
Reference
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THS3001 EVM Board Layouts
Figure 2–2. THS3001 EVM PC Board Layout – Component Side
Figure 2–3. THS3001 EVM PC Board Layout – Back Side
2-3
Reference
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THS3001 Rev. A High-Speed Operational Amplifier EVM Parts List
2.3 THS3001 Rev. A High-Speed Operational Amplifier EVM Parts List
Table 2–2.THS3001 Rev. A EVM Parts List
Manufacturer/Digi-Key
Reference
Description
Size
Part Number
C1, C2
C3, C4
J1
Capacitor, 6.8 µF, 35 V, SM
Capacitor, 0.1 µF, ceramic, 10%, SM 1206 Sprague 11C1201E104M5NT
D
Sprague 293D685X9035D2T
Terminal Block
Digi-Key ED1515–ND
J2, J3, J4
Connector, SMA 50-Ω vertical PC
mount, through-hole
Amphenol ARF1205–ND
R1, R3, R5 Resistor, 49.9 Ω, 1%, 1/8 W, SM
1206 Digi-Key P49.9CTR–ND
1206 Digi-Key P1.0KCTR–ND
SOIC-8 TI THS3001
R2, R4
U1
Resistor, 1 kΩ, 1%, 1/8 W, SM
IC, THS3001, operational amplifier
PCB, THS3001 Rev. A EVM
PCB1
2.4 THS3001 Rev. A EVM Board Layouts
Board layout examples of the THS3001 Rev. A EVM PCB are shown in the
following illustrations. They are not to scale and appear here only as a
reference.
Figure 2–4. THS3001 Rev. A EVM Component Placement Silkscreen and Solder Pads
J1
–VCC
C1
+VCC
C2
J2
GND
+
–IN
+
GND
TEXAS
INSTRUMENTS
R2
INVERTING
J4
R4
C3
Rev. A
NONINVERTING
R1
R3
+IN
GND
R5
U1
C4
J3
SLOP130 Rev A
THS3001 EVM Board
2-4
Reference
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THS3001 Rev. A EVM Board Layouts
Figure 2–5. THS3001 Rev. A EVM PC Board Layout – Component Side
Rev. A
Figure 2–6. THS3001 Rev. A EVM PC Board Layout – Back Side
Rev. A
2-5
Reference
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2-6
Reference
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