Thinking about using LTC1569-7 filter from LTC

[si2030]

Hi there,
I am building a circuit that requires the sine wave to be filtered (low pass) at 120KHz. Anyway I stumbled on to this IC from Linear. I found the part from Linear's filterlab.

I have included the datasheet and a picture of the circuit Filterlab threw up...

My question... by using the circuit provided (my signal will be around 0.5volts P-P) can I use this to be an effective low pass filter for around 120KHz and above?

It also said that the output could "This pin can drive 10k ohm and/or
40pF loads"... what does this mean...

I guess I dont want to buy it and implement it if I have missed something obvious...


Simon

 

[crutschow]

That circuit should do the low-pass function you need.

Be aware that the noise level is about 0.13mV rms. That may not be a problem in your application but need to consider it.

"10k ohm and/or 40pf loads" simply means that it can take any combination of resistance and capacitance load on the output down to a minimum resistance of 10k ohm and a maximum capacitance of 40pF.

The simulation shows a rolloff of about 10dB at 120kHz. Is that what you want?

 

[si2030]

Hi Carl,

I wanted this to filter out noise in a DDS sig generator. This is for a low frequency leg and I am using an analog multiplexer to direct the signal. Regarding the 0.13mV noise of this chip and that the DDS chip puts out a signal around 0.5V p-p should I be worried? ... with regard to this application?

Simon

 

[crutschow]

Hi Carl,

I wanted this to filter out noise in a DDS sig generator. This is for a low frequency leg and I am using an analog multiplexer to direct the signal. Regarding the 0.13mV noise of this chip and that the DDS chip puts out a signal around 0.5V p-p should I be worried? ... with regard to this application?

Since you want to filter out noise, you obviously want less noise than you have with no filter. So what is the level of noise your application can tolerate? I can't answer your question since I don't know that. And if you know that, you can answer your own question.