Description
1.1 Description
The THS4140 EVM is a good example of PCB design and layout for high-speed operational amplifier applications. It is a complete circuit for the high-speed operational amplifier. The EVM is made of the THS4140 high-speed operational amplifier, a number of passive components, and various features and footprints that enable the user to experiment, test, and verify various operational amplifier circuit implementations. The board measures 4.5 inches in length by 2.5 inches in width. Initially, this board is populated for a single-ended input amplifier (see Figure 1-2 for populated circuits). The outputs (VO+ and VO±) can be tested differentially or single ended. Gain is set to one and can be changed by changing the ratios of the feedback and gain resistors (see the device datasheet for recommended resistor values). The user may populate various footprints on the evaluation module board to verify filter designs or perform other experiments. Each input is terminated with a 50-Ωresistor to provide correct line-impedance matching.
1.2 Evaluation Module Features
THS4140 high-speed operational amplifier EVM features include:
JVoltage supply operation range: 5-V to ± 15-V operation (see the device data sheet)
JSingle and differential input and output capability
JNominal 50-Ωinput and output termination resistors. They can be configured according to the application requirement.
JVOCM direct input control (see schematic and the device data sheet)
JVOCM pin can be controlled via transformer center-tap (see schematic)
JShutdown pin control, JU1 (if applicable to the device, see the device data sheet)
JInput and output transformer footprints for changing single-ended signals to differential signals
JFootprint for high-precision, balanced feedback and gain resistors (0.01% or better)
JFootprints for low-pass filter implementation (see application note SLOA054A)
JFootprints for antialiasing filter implementation (see application note SLOA054A)
JDifferential probe terminals on input and output nodes for differential probe insertion
JVarious GND and signal test points on the PCB
JCircuit schematic printed on the back of the EVM
JA good example of high-speed amplifier PCB design and layout
