发明名称 |
Frequency tuning system for tuning a center frequency of an analog bandpass filter |
摘要 |
Based on the insight that the voltage-to-current ratio or gain of a capacitor (Z) at a particular reference frequency is the product of its capacitance value with said reference frequency, a tuning system is disclosed which tunes the center frequency of an analog bandpass filter by tuning the characteristic integrator frequency (fc) of an OTA-C integrator by making the transconductance of the operational transconductance amplifier (OTA) thereof equal to the aforementioned gain at that characteristic frequency. Therefore, the tuning system includes a first tuning path in which the OTA, (or a replica thereof) is included and a second tuning path including another amplifier (B-OTA) "degenerated" by the capacitor (Z) so as to produce the required gain. The gains of both these tuning paths are then equalized by matching means (MM) generating a frequency tuning signal (VTF) which is applied to both OTA and OTA-C.
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申请公布号 |
US5440264(A) |
申请公布日期 |
1995.08.08 |
申请号 |
US19940350705 |
申请日期 |
1994.12.07 |
申请人 |
ALCATEL N.V. |
发明人 |
SEVENHANS, JOANNES M. J.;VAN PAEMEL, MARK G. S. J. |
分类号 |
H03H11/04;H03H11/12;(IPC1-7):H03B5/00 |
主分类号 |
H03H11/04 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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