I am currently working on amplifying the output sine wave of the TG5011 professional signal generator. Below are the specifications for the amplifier I am aiming to create:
- Power Supply: A single supply of either 30V or 36V
- Output Voltage: 30V peak-to-peak (30Vpp)
- DC Offset: 15V DC
- Bandwidth: 100kHz to 30MHz
- Input Voltage: 1V peak-to-peak (1Vpp)
To achieve this, I am employing four cascaded op-amps, configuring two dual op-amp ICs in an inverting configuration with a 15V DC bias (please refer to the attached image). The required slew rate should be a minimum of 3000V/μs, as calculated by the formula SR = 2·π·Vout·f.
However, I have encountered a challenge in realizing this amplifier. Up until now, I have utilized the LM7372, which boasts a bandwidth of 120MHz. I am employing a gain of 3kOhm/1.3kOhm = 2.3 for each stage, theoretically resulting in a bandwidth of approximately 52 MHz. This worked flawlessly for each IC individually, but when connected together, the second IC overheated and ultimately burned out. Upon further investigation, I discovered that the LM7372 has limitations in its output swing voltage, which caused excessive heating and damage to the second IC.
I attempted to use the LM6172 (GBWP = 100 MHz); however, the gain dropped significantly at 15 MHz. I also experimented with the LM7171, but connecting the ICs together produced a substantial amount of harmonics and distortion.
I am now unsure of what I may be doing incorrectly and which op-amp model would be suitable for my application. I had contemplated using Current Feedback Amplifier (CFA) op-amps, but they are not recommended for inverting configurations and may introduce stability issues.
Do you have any recommendations for an op-amp model that I can employ to achieve my goal? I have attached an image of the schematic I am using for all the op-amps and the PCB design layout.
Note. I am not using the filter in the schematic.
I sincerely appreciate your assistance in advance.