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    • 5. 发明申请
    • APPARATUS AND METHODS FOR TUNING BANDPASS FILTERS
    • 用于调谐滤波器的装置和方法
    • WO99040679A1
    • 1999-08-12
    • PCT/US1999/002424
    • 1999-02-04
    • H03H11/04H03J3/18H04B1/26
    • H03H11/0422H03J3/18
    • A signal having a substantially uniform spectral distribution, e.g., a flat noise signal such as a signal ground, is provided at the input of a bandpass filter such as an IF filter of a receiver circuit, to thereby produce an output signal at the output of the bandpass filter. The output signal is processed in a limiter to produce a limited signal. An average frequency of the limited signal is determined, and the bandpass filter is adjusted based on the determined average frequency. According to one embodiment of the present invention, the bandpass filter comprises a Gm-C filter having a transconductance, and the filter is adjusted by adjusting the transconductance of the Gm-C filter based on the determined average frequency. According to another aspect of the present invention, a desired center frequency for the bandpass filter is identified. A resolution and a desired confidence interval are also identified. The number of samples of the limited signal needed to achieve the identified desired resolution and confidence interval is determined based on the identified desired center frequency. An average frequency is determined by sampling the limited signal to obtain a plurality of samples, the number of the plurality of samples being at least as great as the determined number of samples of the limited signal to achieve the identified desired resolution and confidence level, and determining the average frequency from the plurality of samples. The bandpass filter is adjusted based on the determined average frequency to achieve a center frequency for the bandpass filter that is within a predetermined range with respect to the desired center frequency. Related apparatus are also discussed.
    • 在诸如接收机电路的IF滤波器的带通滤波器的输入处提供具有基本上均匀的频谱分布的信号,例如平面噪声信号,例如信号地,从而在输出端产生输出信号 带通滤波器。 在限幅器中处理输出信号以产生有限的信号。 确定有限信号的平均频率,并且基于所确定的平均频率来调整带通滤波器。 根据本发明的一个实施例,带通滤波器包括具有跨导的Gm-C滤波器,并且通过基于确定的平均频率调整Gm-C滤波器的跨导来调节滤波器。 根据本发明的另一方面,识别了用于带通滤波器的期望中心频率。 还确定了分辨率和期望的置信区间。 基于所识别的期望中心频率来确定实现所识别的期望分辨率和置信区间所需的受限信号的采样数。 通过对受限信号进行采样以获得多个样本来确定平均频率,多个采样的数量至少等于所确定的限制信号样本的数量,以达到所识别的期望分辨率和置信度,以及 确定来自多个样本的平均频率。 基于确定的平均频率来调整带通滤波器,以实现相对于期望的中心频率在预定范围内的带通滤波器的中心频率。 还讨论了相关装置。