An automatic tuning scheme using envelope detectors and simple mixed-mode circuitry is discussed. The method is developed especially for filters with large Q values and can be used at very high operating frequencies. The circuit was designed in a 1.2 /spl mu/m CMOS process with a 3 V single supply voltage. As a demonstration filter, a second-order g/sub m/-C bandpass section is used, but the method can also be applied to lowpass and highpass sections. The measured frequency tuning error is less than 0.3% for filters with Q<80 operating in the range of 105 MHz-120 MHz.
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机译：讨论了使用包络检波器和简单混合模式电路的自动调谐方案。该方法专为具有大Q值的滤波器而开发，可以在很高的工作频率下使用。该电路采用1.2 V / spl mu / m CMOS工艺设计，单电源电压为3V。作为演示滤波器，使用了二阶g / sub m / -C带通部分，但是该方法也可以应用于低通和高通部分。对于Q <80且工作在105 MHz至120 MHz范围内的滤波器，测得的频率调谐误差小于0.3％。
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