Design Techniques for Tunable Transresistance-C VHF Bandpass Filters

Ping Hsing Lu, Chung-Yu Wu, Ming Kai Tsai

Research output: Contribution to journalArticle

15 Scopus citations


In this paper, a tunable wideband linear transresistance (Rm) amplifier is proposed and analyzed. Using the tunable Rm amplifier, a new transresistance-capacitor (Rm-C) differentiator is designed. Considering the intrinsic capacitances of the MOS transistors as filter elements, this Rm -C configuration can be regarded as a very high frequency (VHF) bandpass biquadratic filter. The proposed biquad has a simple structure and thus occupies a small chip area and consumes little power. Moreover, higher-order VHF bandpass filters can be realized by directly cascading the biquads. Experimental results have successfully proven the capability of the proposed new filter implementation method in realizing VHF bandpass filters with the center frequency higher than 100 MHz when Cd = 1 pF. The deviations of the measured center frequency fo and quality factor Q of the fabricated bandpass filter from the simulated results are less than 8%. The deviation of the center frequency can be post-tuned by adjusting the control voltages VCN and VCP of the tunable Rm amplifier. With 1 pF differentiating capacitor, the center frequency of the fabricated VHF Rm-C bandpass filters can be tuned in a wide range larger than 30 MHz. The measured maximum signal level is 25 mVrms and the dynamic range is 47 dB. The chip area is 0.05 mm2 and power consumption is 5.05 mW with ±2.5 V power supply.

Original languageEnglish
Pages (from-to)1058-1067
Number of pages10
JournalIEEE Journal of Solid-State Circuits
Issue number9
StatePublished - 1 Jan 1994

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