Lutz von Wangenheim

5 Questions 495 Answers 0 Followers

Questions related from Lutz von Wangenheim

Who knows this characteristic of the "Butterworth" approach?

By chance, I discovered an interesting property of the "Butterworth" approximation: The product of the quality factors Qp for each pole is constant. This applies to any filter order n. * Even n:...

03 March 2019 9,628 10 View

What is the input resistance of a differential amplifier?

Simple question (back to basics): For a classical diff. amplifier (Q1 and Q2, finite dynamic resistance re in the common emitter leg): How do we calculate the input resistance at the base of Q1 ?

03 March 2019 4,514 35 View

Where are the limitations of idealized opamp models?

Are there opamp-based circuits which, normally, are designed assuming idealized opamp parameters - however, when simulated based on idealized opamp models (VCVS) they do not function at all?

09 September 2017 1,281 7 View

What are the restrictions for using describing functions in oscillator design?

I am aware that linear oscillators must contain a non-linear part to limit loop gain (or amplitudes) after the start-up phase. Simple case: Amplitude clipping due to supply rails. Then, using the...

07 July 2013 7,498 12 View

How to demonstrate a negative group velocity?

My question is: Does anybody know if resp. how it is possible to demonstrate the case of a negative group velocity using any standard simulation program?

07 July 2013 9,574 3 View