! ! User’s Guide September 2000 Mixed-Signal Products SLOU075
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Preface Related Documentation From Texas Instruments THS4081, THS4082 175-MHz LOW-POWER HIGH-SPEED AMPLIFIERS (literature number SLOS274) This is the data sheet for the THS4082 operational amplifier integrated circuit that is used in the THS4082 evaluation module. FCC Warning This equipment is intended for use in a laboratory test environment only.
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Running Title—Attribute Reference Contents 1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1 Feature Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1.
Running Title—Attribute Reference Figures 1–1 1–2 1–3 1–4 1–5 1–6 1–7 1–8 1–9 2–1 2–2 2–3 2–4 THS4082 Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 THS4082 EVM Schematic: Noninverting Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 THS4082 EVM Schematic: Inverting Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1 General This chapter details the Texas Instruments (TI) THS4082 dual high-speed operational amplifier evaluation module (EVM), SLOP239. 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 discussions on high-speed amplifier design and thermal considerations. Topic Page 1.1 Feature Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Feature Highlights 1.
Description 1.2 Description The TI THS4082 dual high-speed operational amplifier evaluation module (EVM) is a complete dual high-speed amplifier circuit. It consists of the TI THS4082 dual low-noise high-speed operational amplifier IC, along with a small number of passive parts, mounted on a small circuit board measuring approximately 1.9 inch by 2.2 inch (Figure 1–1).
THS4082 EVM Noninverting Operation 1.3 THS4082 EVM Noninverting Operation The THS4082 EVM is shipped preconfigured for dual-channel noninverting operation, as shown in Figure 1–2. Note: Compensation capacitors C3 and C6 are not installed. Figure 1–2. THS4082 EVM Schematic: Noninverting Operation C3 x µF J2 –VCC GND +VCC 1 –VCC 2 3 C2 6.8 µF C1 6.8 µF +VCC R5 1 kΩ R6 1 kΩ 2 +VCC C5 0.1 µF 8 U1:A THS4082 – J1 R7 49.9 Ω J3 VOUT1 1 VIN1 R1 49.9 Ω R3 0Ω 3 + C4 0.
THS4082 EVM Noninverting Operation 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. Note: External factors can significantly affect the effective gain of the EVM.
Using the THS4082 EVM in the Noninverting Mode 1.4 Using the THS4082 EVM in the Noninverting Mode The THS4082 EVM operates from power-supply voltages ranging from ± 5 V to ± 15 V. As shipped, the EVM is configured for noninverting operation and the gain is set to 2. Signal inputs on the module are terminated for 50-Ω nominal source impedance. An oscilloscope is typically used to view and analyze the EVM output signal.
THS4082 EVM Inverting Operation 1.5 THS4082 EVM Inverting Operation Although the THS4082 EVM is shipped preconfigured for dual-channel noninverting operation, it can be reconfigured for inverting operation by making the following component changes: 1) Move resistor R3 to the R2 location and R5 to the R4 location on the board. 2) Move resistor R11 to the R10 location and R13 to the R12 location on the board. This configuration is shown in Figure 1–3.
THS4082 EVM Inverting Operation The gain of the EVM can easily be changed to support a particular application by simply changing the ratio of resistors R6 and R4 (channel 1) and R14 and R12 (channel 2) as described in the following equation: Inverting Gain –R F RG –R6 and –R14 R4 R12 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.
Using the THS4082 EVM in the Inverting Mode 1.6 Using the THS4082 EVM in the Inverting Mode The THS4082 EVM operates from power-supply voltages ranging from ± 5 V to ± 15 V. As shipped, the EVM is configured for noninverting operation. Move the resistors as detailed above to configure the EVM for noninverting operation, which sets the gain to –1. Signal inputs on the module are terminated for 50-Ω nominal source impedance. An oscilloscope is typically used to view and analyze the EVM output signal.
THS4082 EVM Differential Input 1.7 THS4082 EVM Differential Input The THS4082 EVM is shipped preconfigured for dual-channel, single-ended noninverting operation. It can be reconfigured for single-channel, differential operation, either noninverting or inverting. 1.7.1 Differential Input, Noninverting Operation Configure the THS4082 EVM for differential noninverting operation by removing two resistors and adding a resistor on the board: 1) Remove resistors R1 and R9.
THS4082 EVM Differential Input The gain of the EVM can easily be changed to support a particular application by simply changing the ratio of resistors R6 and R5 (channel 1) and R14 and R13 (channel 2) as described in the following equation: Noninverting Gain 1 RF RG 1 R6 and 1 R14 R5 R13 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.
THS4082 EVM Differential Input Figure 1–5. THS4082 EVM Schematic: Differential Input (Inverting Operation) C3 x µF J2 –VCC GND +VCC 1 –VCC 2 3 C2 6.8 µF C1 6.8 µF +VCC R6 1 kΩ +VCC R4 1 kΩ J1 VIN1 2 – 8 C5 0.1 µF U1:A THS4082 R7 49.9 Ω J3 VOUT1 1 + 3 C4 0.1 µF 4 R2 0Ω C6 x µF –VCC R8 100 Ω R14 1 kΩ R12 1 kΩ J4 VIN2 6 – + 5 U1:B THS4082 R15 49.
THS4082 EVM Differential Input 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. Note: External factors can significantly affect the effective gain of the EVM.
Using the THS4082 EVM With Differential Inputs 1.8 Using the THS4082 EVM With Differential Inputs The THS4082 EVM operates from power-supply voltages ranging from ± 5 V to ± 15 V. Move resistors on the board as detailed above for either noninverting or inverting operation to configure the EVM for differential input operation. Signal inputs on the module are terminated for 50-Ω nominal source impedance. An oscilloscope is typically used to view and analyze the EVM output signal.
THS4082 EVM Performance 1.10 THS4082 EVM Performance Figure 1–6 shows the typical frequency response of the THS4082 EVM using the noninverting configuration (G = 2). Typical – 0.1 dB bandwidth is 22 MHz and – 3-dB bandwidth is 75 MHz with both a ±15-V power supply and a ±5-V power supply. Figure 1–6. THS4082 EVM Frequency Response With Gain = 2 7 6 Output Amplitude – dB 5 4 3 2 1 0 –1 100k VCC = ±5 V and ±15 V VI = 0.
General High-Speed Amplifier Design Considerations 1.11 General High-Speed Amplifier Design Considerations The THS4082 EVM layout has been designed and optimized for use with high-speed signals and can be used as an example when designing THS4082 applications. Careful attention has been given to component selection, grounding, power supply bypassing, and signal path layout.
General PowerPADE Design Considerations 1.12 General PowerPAD Design Considerations The THS4082DGN IC is mounted in a special package incorporating a thermal pad that transfers heat from the IC die directly to the PCB. The PowerPAD package is constructed using a downset leadframe. The die is mounted on the leadframe but is electrically isolated from it. The bottom surface of the lead frame is exposed as a metal thermal pad on the underside of the package and makes physical contact with the PCB.
General PowerPADE Design Considerations 8) With these preparatory steps in place, the THS4082DGN IC is simply placed in position and run through the solder reflow operation as any standard surface-mount component. This results in a part that is properly installed. The actual thermal performance achieved with the THS4082DGN in its PowerPAD package depends on the application.
General PowerPADE Design Considerations Correct PCB layout and manufacturing techniques are critical for achieving adequate transfer of heat away from the PowerPAD IC package. More details on proper board layout can be found in the THS4081, THS4082 175-MHz Low-Power High-Speed Amplifiers data sheet (literature number SLOS274).
1-20 General
Chapter 2 Reference This chapter includes a complete schematic, parts list, and PCB layout illustrations for the THS4082 EVM. Topic Page 2.1 THS4082 EVM Complete Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–2 2.2 THS4082 Dual High-Speed Operational Amplifier EVM Parts List . . 2–3 2.3 THS4082 EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
THS4082 EVM Complete Schematic 2.1 THS4082 EVM Complete Schematic Figure 2–1 shows the complete THS4082 EVM schematic. The EVM is shipped preconfigured for dual-channel, single-ended inverting operation. Components showing a value of X are not supplied on the board, but can be installed by the user to reconfigure the EVM for noninverting and/or differential operation. Figure 2–1. THS4082 EVM Schematic C3 x µF J2 –VCC GND +VCC 1 –VCC 2 3 C1 6.8 µF C2 6.
THS4082 Dual High-Speed Operational Amplifier EVM Parts List 2.2 THS4082 Dual High-Speed Operational Amplifier EVM Parts List Table 2–1. THS4082 EVM Parts List Reference Description Size Manufacturer/Supplier Part Number C1, C2 Capacitor, 6.8 µF, 35 V, Tantalum, SM C4, C5 Capacitor, 0.1 µF, Ceramic, 10%, SM J2 3-Pin terminal block (On Shore Tech.) Digi-Key ED1515–ND J1, J3, J4, J5 Connector, SMA 50-Ω vertical PC mount, through-hole Amphenol ARF1205–ND R1, R7, R9, R15 Resistor, 49.
THS4082 EVM Board Layouts 2.3 THS4082 EVM Board Layouts Board layout examples of the THS4082 EVM PCB are shown in the following illustrations. They are not to scale and appear here only as a reference. Figure 2–2.
THS4082 EVM Board Layouts Figure 2–3.
THS4082 EVM Board Layouts Figure 2–4.
