Hi

I am a student and I want to design a low pass filter circuit. I have searched few research articles and I got to know that in low-pass filter circuit mostly Gm-C filters are considered. I want to ask to questions:

1. Is OTA-C and Gm-C filter one and the same thing?

2. Why OTA is used for the design of low-pass filter. In research article in introduction part it only mentions like 'OTA is one of the most important building block used in signal processing applications and filter design' etc.. There isn't mentioned why OTA is used? Any special reason of preferring OTA over Op-amps or any other active block. Any logical reason of preferring OTA is not giving.

 

In research article in introduction part it only mentions like 'OTA is one of the most important building block used in signal processing applications and filter design'

I've been doing analog circuit design professionally for more than 40 years now, and have designed scores of filters of various kinds, and I have NEVER-- not even once-- used an OTA in a filter (or in any other kind of circuit); so I think the statement you quoted from the research article is rather overblown. Are OTAs sometimes used in filter designs? Yes, of course they are. Are they the ONLY way to design a filter, or even the most common way? Absolutely not.

 

Hello,

An OTA can be usefull when you want to make a voltage controlled device.
This can be a filter, amplifier or oscillator.
The datasheets of the LM13600 and LM13700 will show you some examples.

Bertus

 

I've been doing analog circuit design professionally for more than 40 years now, and have designed scores of filters of various kinds, and I have NEVER-- not even once-- used an OTA in a filter (or in any other kind of circuit); so I think the statement you quoted from the research article is rather overblown. Are OTAs sometimes used in filter designs? Yes, of course they are. Are they the ONLY way to design a filter, or even the most common way? Absolutely not.

Thank you for your reply.
If I see paper related to low frequency applications like biomedical applications (EEG, ECG or EMG) low pass filters are used by first designing OTA and then filter i.e OTA-C filter. What other ways could be preferred to design filter?

Thankyou