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19th February 2019, 07:50 #21
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Re: How to implement a transfer function with discrete components
OK thanks. Just for information, how is a LHPZ + single pole combo of unequal pole/zero frequency realized pls?
And just in case I needed to implement the TF in 'z' domain, how could I do so?
Which discrete op amp IC would you suggest for physical realization of the TF? Though there are many op amps available, which one would be adept in the job?
Finally during testing, what characteristics does one need to check for a filter? I know mainly about 3 dB frequency and that the roll down/up rate to be 20dB

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19th February 2019, 16:37 #22
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Re: How to implement a transfer function with discrete components
OK. Thanks for the clarifications. I could calculate the values of DC gain and pole here (inverting gain of the amplifier and 1/RC). How to calculate (or basically select components) for the value of zero (zero at 1).
Also to implement a pole, one could use either a first order low pass or integrator ckt. Which one to prefer when? Similarly for implementing a zero, one could use a first order high pass or differentiator ckt. Which one to use when?
I myself don't know the use of the TF. I was just given to just implement it on the bred board and see if it can be realized.
Regards,
Arvind Gupta

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19th February 2019, 17:02 #23
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Re: How to implement a transfer function with discrete components
I myself don't know the use of the TF. I was just given to just implement it on the bred board and see if it can be realized.
There are however additional problems related to input signal level and OP voltage swing. The given circuit has some gain of 5 the first stage and gain < 1 in the second stage, thus there's a chance to get signal clipping in the first stage output. One possible solution is to flip first and second stage, or implement the transfer function in a different way, depending on the actual requirements.

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21st February 2019, 19:11 #24
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Re: How to implement a transfer function with discrete components
OK. But the basic question remains. How to select circuit values for fixing the zero at s=1 in your last two ckt diagrams (and in my TF)?
Regards,
Arvind Gupta

22nd February 2019, 09:42 #25
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Re: How to implement a transfer function with discrete components
As long you are doing an exercise without actual requirements, absolute component values don't really matter. I started with feasible capacitor values in my example.
As for relative component values (resistor ratios, RC time constants), I sketched my method in post #19:
 have a principle circuit topology and it's general transfer function
 apply comparison of coefficients
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