Hi there,
I've spent several days trying to figure out this bridged T circuit and the basic formulas someone would need. Unfortunately, there were no good easy formulas for Q or bandwidth so I made/derived a formulas for them. They are estimates only, but quick and easy. Here is a summary of everything I found. The Q formula and bandwidth formulas I came up with and if you'd like to see how I did it you can check out what I did. I basically used the high pass section to get the low cutoff frequency and low pass section to get the high cutoff frequency. It was a lot easier than using the inverse function of the transfer function, which seemed awfully difficult.
https://sites.google.com/site/garydavenportelectronics/home/bridgedtnotchfilter
I would appreciate any critiques/suggestions about this because its quite complicated.
I've spent several days trying to figure out this bridged T circuit and the basic formulas someone would need. Unfortunately, there were no good easy formulas for Q or bandwidth so I made/derived a formulas for them. They are estimates only, but quick and easy. Here is a summary of everything I found. The Q formula and bandwidth formulas I came up with and if you'd like to see how I did it you can check out what I did. I basically used the high pass section to get the low cutoff frequency and low pass section to get the high cutoff frequency. It was a lot easier than using the inverse function of the transfer function, which seemed awfully difficult.
https://sites.google.com/site/garydavenportelectronics/home/bridgedtnotchfilter
I would appreciate any critiques/suggestions about this because its quite complicated.
I seem to recall that the Q of a basic RC twin-T filter is 0.25. The bridged filter should be similar. The twin-T, with the correct values, gives a theoretically infinite notch.
The twin-T can be bootstrapped to sharpen the notch.
The twin-T can be bootstrapped to sharpen the notch.
On your webpage, it appears that you have the HPF and LPF reversed, i.e., R1/C2 is the LPF, and C1/R2 is the HPF.
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