This letter introduces a 4th order active RC complex filter with 1.SMHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than -60dB and the image rejection ratio is greater than...This letter introduces a 4th order active RC complex filter with 1.SMHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than -60dB and the image rejection ratio is greater than 60dB. A novel technique is also proposed in this letter to automatically adjust the variation of the time constant. The advantages of the proposed method are its high precision and simplicity. Using 5bits control words, the tuning error is less than ±1.6%.展开更多
This paper describes a complete baseband chain for both GSM and WCDMA receivers with a SMIC 0.35μm mixed signal process. The chain consists of a dual-mode,highly linear, fourth order Chebyshev active RC filter and th...This paper describes a complete baseband chain for both GSM and WCDMA receivers with a SMIC 0.35μm mixed signal process. The chain consists of a dual-mode,highly linear, fourth order Chebyshev active RC filter and three VGA stages. The filter is designed to meet the bandwidth specifications of the GSM and WCDMA standards and share the maximum number of components between the two modes to reduce manufacturing cost. The design is free of DC-offset and has an inter-stage high-pass filter, and operational amplifiers with adjustable GBW are used to minimize GSM-mode power consumption. The measured noise figures are 27. 3 and 42dBm in WCDMA and GSM modes,respectively, at the maximum gain. The IIP3 is 40dBm at unit gain in the WCDMA mode,and the circuit consumes 47.0mW. The IIP3 is 28dBm in the GSM mode,and the circuit consumes 31.8mW. The supply voltage is 3.3V.展开更多
An active-RC low-pass filter of 5MHz cutoff frequency with a tuning architecture is proposed. It is implemented in 0. 18μm standard CMOS technology. The accuracy of the tuning system is improved to be within （ - 1.2...An active-RC low-pass filter of 5MHz cutoff frequency with a tuning architecture is proposed. It is implemented in 0. 18μm standard CMOS technology. The accuracy of the tuning system is improved to be within （ - 1.24%, ＋ 2.16%） in measurement. The chip area of the tuning system is only a quarter of that of the main-filter. After tuning is completed, the tuning system will be turned off automatically to save power and to avoid interference. The in-band 3rd order harmonic input intercept point （IIP3） is larger than 16. ldBm, with 50Ω as the source impedance. The input referred noise is about 36μVrms The measured group delay variation of the filter between 3 and 5MHz is only 24ns,and the filter power consump- tion is 3.6roW. This filter with the tuning system is realized easily and can be used in many wireless low-IF receiver applications, such as global position systems （GPS）, global system for mobile communications （GSM） and code division multiple access （CDMA） chips.展开更多
基金Supported by the Key Project of the National Natural Science Foundation of China (No.60437030) the Tianjin Natural Science Foundation (No.05YFJMJC01400).
文摘This letter introduces a 4th order active RC complex filter with 1.SMHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than -60dB and the image rejection ratio is greater than 60dB. A novel technique is also proposed in this letter to automatically adjust the variation of the time constant. The advantages of the proposed method are its high precision and simplicity. Using 5bits control words, the tuning error is less than ±1.6%.
文摘This paper describes a complete baseband chain for both GSM and WCDMA receivers with a SMIC 0.35μm mixed signal process. The chain consists of a dual-mode,highly linear, fourth order Chebyshev active RC filter and three VGA stages. The filter is designed to meet the bandwidth specifications of the GSM and WCDMA standards and share the maximum number of components between the two modes to reduce manufacturing cost. The design is free of DC-offset and has an inter-stage high-pass filter, and operational amplifiers with adjustable GBW are used to minimize GSM-mode power consumption. The measured noise figures are 27. 3 and 42dBm in WCDMA and GSM modes,respectively, at the maximum gain. The IIP3 is 40dBm at unit gain in the WCDMA mode,and the circuit consumes 47.0mW. The IIP3 is 28dBm in the GSM mode,and the circuit consumes 31.8mW. The supply voltage is 3.3V.
文摘An active-RC low-pass filter of 5MHz cutoff frequency with a tuning architecture is proposed. It is implemented in 0. 18μm standard CMOS technology. The accuracy of the tuning system is improved to be within （ - 1.24%, ＋ 2.16%） in measurement. The chip area of the tuning system is only a quarter of that of the main-filter. After tuning is completed, the tuning system will be turned off automatically to save power and to avoid interference. The in-band 3rd order harmonic input intercept point （IIP3） is larger than 16. ldBm, with 50Ω as the source impedance. The input referred noise is about 36μVrms The measured group delay variation of the filter between 3 and 5MHz is only 24ns,and the filter power consump- tion is 3.6roW. This filter with the tuning system is realized easily and can be used in many wireless low-IF receiver applications, such as global position systems （GPS）, global system for mobile communications （GSM） and code division multiple access （CDMA） chips.
