Simple? inverting op amp

[Abelinkkin]

Hello everyone,

Maybe I am just missing something here but for the life of me I can not get this inverting op amp I am building to work. I am using a MCP6269 op amp because the signal i am putting into it is a 5Mhz sin wave. All i need to do is invert the signal so I can use it in the BPSK transmitter i am building. I am hooking it up in the generic inverting op amp way. Seen here.
Op-amp Varieties

All i need is an inverted signal so I know about usign the same value resistors to get a gain of -1. i have tried dozens of different sized resisitors and nothing works.

Maybe one of yall know something I dont. Thx for the help.

Abe

 

[Nigel Goodwin]

Google doesn't even find that number? - but opamps generally don't go that high.

 

[ericgibbs]

Look at this pdf for th NE592 video amp, it obsolete, but equivalent opa's are available.

Post the datasheet for that MCP opa you are using.

 

[Abelinkkin]

Here is the data sheet. Sorry mistyped the number in the original post. Its the MCP 6294. Does the GBWP of 10Mhz mean it is capable of handling input signals of 5Mhz?

 

[ericgibbs]

Here is the data sheet. Sorry mistyped the number in the original post. Its the MCP 6294. Does the GBWP of 10Mhz mean it is capable of handling input signals of 5Mhz?

hi,
How are you connecting the 5MHz signal and whats the amplitude of the signal.

 

[Abelinkkin]

The 5Mhz signal is just from a function generator with the positive terminal going into R1 and the negative terminal gonig to ground. I have tried varying the amplitude of the signal from 0 through 10V with no change.

 

[ericgibbs]

The 5Mhz signal is just from a function generator with the positive terminal going into R1 and the negative terminal gonig to ground. I have tried varying the amplitude of the signal from 0 through 10V with no change.

I was wondering if the output of the function generator has a 'dc' offset thats causing a problem, have you tried a low value coupling cap, say 1000picoF, from the gen to the non inv input.

Connect a 1M resistor from the non inv to the 0V of the MCP

 

[crutschow]

It should handle 5MHz signals at a gain of -1 if properly configured. The resistors should be 1k ohm or less to minimize response peaking. You will likely also need a few pF cap across the feedback resistor to eliminate any residual response peaking.

Does your circuit work at lower frequencies? Circuit layout and decoupling is critical at 5MHz. You should have a well laid out PCB with a ground plane for proper circuit operation. Note the layout requirements on pages 12 and 13 of the data sheet.

 

[audioguru]

The datasheet for the MCP6294 shows a very low max supply voltage. It also shows that its max output at 5MHz is only 0.35V p-p.

Please attach your schematic complete with the dual-polarity supply voltages.