Circuits, Systems and Signal Processing pp 117-124 | Cite as

# Design of Parallel-T Resistance–Capacitance Networks For Maximum Selectivity

A simple analysis is presented for obtaining an expression for the transfer function and hence the selectivity, *Q* _{T}, of a general parallel-T resistance–capacitance network. The maximum value of *Q* _{T} obtainable by a suitable choice of elements is shown to be \( \tfrac{1}{2} \). A design procedure for approaching this maximum value is given.An expression for the selectivity, *Q* _{A}, of an amplifier using a general parallel-T resistance–capacitance network in the negative feedback line has been deduced and the advantages of having an increased *Q* _{T} explained. Parallel-T *RC* is an important network and you cannot do without it, if you wish to remain in circuit design.An expression has been given for estimating the departure from linearity of the amplitude response characteristic at a particular frequency. This is used to find an optimum value of *Q* _{T} for best performance of the network as an F.M. discriminator at low frequencies. It is shown that the required value of *Q* _{T} is very near its maximum value.

## Keywords

Parallel-T RC network Selectivity Selective amplifier## Notes

### Acknowledgments

The author is indebted to Prof. J. N. Bhar, D.Sc., F.N.I., and to Dr. A. K. Choudhury, M.Sc., D. Phil., for their kind help and advice in the preparation of this chapter.

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