Design, Fabrication, and Comparative Study of Electronically Tunable Active Filters
The Kerwin-Huelsman Newcomb (KHN) biquad is the natural choice for use as a ‘universal’ filter building block out of the several existing 3-amplifier biquadratic filter sections based on the two integrator loop or state variable realization of 2nd order systems. A modified version of the KHN biquad,...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi Limited
1995-01-01
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| Series: | Active and Passive Electronic Components |
| Online Access: | http://dx.doi.org/10.1155/1995/78209 |
| Summary: | The Kerwin-Huelsman Newcomb (KHN) biquad is the natural choice for use as a ‘universal’ filter building block out of the several existing 3-amplifier biquadratic filter sections based on the two integrator loop or state variable realization of 2nd order systems. A modified version of the KHN
biquad, which is electronically tunable almost linearly over a decade range of center frequency, is
presented. For electronic tunability, instead of the direct use of a FET as a voltage variable resistance
to control the time constants of the integrators, a novel approach of using voltage-controlled variable-gain
amplifiers at the inputs of both the integrators and one immediately after the input signal has been
suggested. The circuit is suitable for use as a tunable universal filtering module and can be easily
digitally programmed. |
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| ISSN: | 0882-7516 1563-5031 |