Single Active Parameter Tunable Simple Band-Pass Filter: Methods for Tunability Range Extension

Single Active Parameter Tunable Simple Band-Pass Filter: Methods for Tunability Range Extension

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This paper compares three possible methods of adjusting center frequency in a second order band-pass filter using a single active parameter. Limited range of driving voltages serving for tuning of electronically controllable applications is the problem of modern low-voltage systems due to reduced power supply voltage. Therefore, methods how to obtain similar bandwidths of adjustability in comparison to standard linear control applied in systems with DC driving voltage/current range below one decade should be studied. Lossless integrator (its transconductance subpart) implemented in the structure of the filter was solved as three different subcircuits allowing three different methods of its adjusting, i.e. linear, quadratic and exponential dependence of transconductance gm on DC driving voltage VSET. This results to square root, linear and exponential dependence of center frequency of the filter on VSET. The last method allows to reach at least a four-times wider range of tunability of center frequency in comparison to standard implementation of a linearly controllable integrator in the same range of VSET. PSpice simulations confirm intended features of the proposed methods.

This paper compares three possible methods of adjusting center frequency in a second order band-pass filter using a single active parameter. Limited range of driving voltages serving for tuning of electronically controllable applications is the problem of modern low-voltage systems due to reduced power supply voltage. Therefore, methods how to obtain similar bandwidths of adjustability in comparison to standard linear control applied in systems with DC driving voltage/current range below one decade should be studied. Lossless integrator (its transconductance subpart) implemented in the structure of the filter was solved as three different subcircuits allowing three different methods of its adjusting, i.e. linear, quadratic and exponential dependence of transconductance gm on DC driving voltage VSET. This results to square root, linear and exponential dependence of center frequency of the filter on VSET. The last method allows to reach at least a four-times wider range of tunability of center frequency in comparison to standard implementation of a linearly controllable integrator in the same range of VSET. PSpice simulations confirm intended features of the proposed methods.

Adjustable integrator; band-pass filter; center frequency control; electronic control; exponential control; tunability range extension

Adjustable integrator; band-pass filter; center frequency control; electronic control; exponential control; tunability range extension

ŠOTNER, R.; PETRŽELA, J.; DOMANSKÝ, O.; LANGHAMMER, L.; DOSTÁL, T.

2018

24.06.2017

Dept. of Microelectronics and Computer Science, Lodz University of Technology, Poland

Bydgoszcz, Poland

978-83-63578-11-4

Proceedings of the 24th International Conference “Mixed Design of Integrated Circuits and Systems”

318

323

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