Title :
The design of CMOS continuous-time VHF current and voltage-mode lowpass filters with Q-enhancement circuits
Author :
Wu, Chung-Yu ; Hsu, Heng-Shou
Author_Institution :
Dept. of Electron. Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan
fDate :
5/1/1996 12:00:00 AM
Abstract :
In this paper, very high frequency (VHF) current and voltage biquadratic lowpass filters implemented directly by the linear wideband finite-gain current and voltage amplifiers, respectively, are proposed and analyzed. A new Q-enhancement circuit which consists of a finite-gain wideband tunable voltage amplifier and a Miller capacitor is also proposed. It can increase the maximum-gain frequency fM, and enhance the maximum-gain quality factor QM of the VHF lowpass filters. Experimental results have successfully verified the capability of the proposed new filter implementation method in realizing both VHF current and voltage lowpass filters with maximum-gain frequency fM tunable in the range of 148 MHz to 92 MHz. It is also shown from experimental results that the VHF current lowpass biquad with the Q-enhancement circuit has the maximum-gain frequency fM near 185 MHz and the maximum-gain quality factor QM up to 18.5. A fourth-order Chebyshev current lowpass filter with the cut-off frequency of 190 MHz has been successfully designed by using the current biquads with Q-enhancement circuits
Keywords :
CMOS analogue integrated circuits; Chebyshev filters; Q-factor; VHF filters; biquadratic filters; continuous time filters; low-pass filters; 148 to 92 MHz; 185 MHz; 190 MHz; CMOS continuous-time VHF filters; Miller capacitor; Q-enhancement circuits; biquadratic lowpass filters; current amplifiers; current-mode lowpass filters; cut-off frequency; filter implementation method; fourth-order Chebyshev current lowpass filter; linear wideband finite-gain amplifiers; maximum-gain frequency; maximum-gain quality factor; tunable amplifier; voltage amplifiers; voltage-mode lowpass filters; Band pass filters; Broadband amplifiers; Capacitors; Design methodology; Frequency; Nonlinear filters; Q factor; Tunable circuits and devices; VHF circuits; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
