| 摘要 |
The quality or Q factor of a one-gate network consisting of an L-C circuit (C1, L) and an operational amplifier (4) is improved by a factor of 2 to 4 by the negative input resistance of the amplifier (4). In this way, the oscillating circuit can be made more useable for band pass filters at low frequencies, for which the aim is to achieve a low outlay on components and space. They are preferably used to filter out ambient sound signals, which are transmitted below the speech band, and would otherwise require relatively extensive coils for a high Q factor. <IMAGE>
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