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The LMH32404RHFEVM is an evaluation module (EVM) for the LMH32404RHF differential output transimpedance amplifier. The EVM features a transformer to convert the output to a 50-Ω single-ended connection for easy measurement with standard test equipment, and the option to convert to fully-differential DC-coupled signals. The input is 50-Ω matched and configured by default to receive a voltage input that is converted to a current through a 2-kΩ resistor, but can be reconfigured to receive a true current input with optional photodiode bias connections on the back of the board. The EVM also includes easy-to-use jumpers to control the device gain, input bias current cancellation, and shutdown functions.
Table 2-1 lists the typical performance specifications for the LMH32404RHFEVM.
Specification | Typical Value Range |
---|---|
Single-supply voltage range (VEE = ground) | 3 V to 3.65 V |
Quiescent current per channel | 28 mA |
Differential output voltage swing (VCC = 3.3 V, 100-Ω load) | 5 VPP |
Linear output current (VCC = 3.3 V, 25-Ω load) | 26.6 mA |
The LMH32404RHFEVM is equipped with a wire socket to easily connect power. The positive supply input is labeled VDD and ground is labeled GND.
The LMH32404RHFEVM is equipped with SMA connectors for easy connection of signal generators and analysis equipment. As shipped, the EVM is configured for a single-ended input and output, both with 50-Ω termination. The differential output of the amplifier is converted to a single-ended output through transformer T1 on the board. OUT+ is the output connector for single-ended output signals, and is terminated to 50-Ω single-ended. To use the EVM with a DC-coupled differential output, remove resistor R7 and transformer T1, and short the connections across the removed transformer input and outputs. When converting to differential, the output resistors may need to be modified to achieve a desired impedance match. See LMH32404 250 MHz, Quad-channel, Differential Output Transimpedance Amplifier applications section, schematics, and layouts for more details and instructions on how to reconfigure the EVM.