Title :
A High-IIP3 Third-Order Elliptic Filter With Current-Efficient Feedforward-Compensated Opamps
Author :
Krishnapura, Nagendra ; Agrawal, Abhishek ; Singh, Sameer
Author_Institution :
Dept. of Electr. Eng., Indian Inst. of Technol., Chennai, India
fDate :
4/1/2011 12:00:00 AM
Abstract :
A low-distortion active filter is realized using current-efficient feedforward-compensated operational amplifiers in the integrators and feedforward current injection in the summing amplifier. A third-order elliptic low-pass filter with two possible bandwidth settings of 17 and 8.5 MHz consumes 1.8 mW from a 1.8-V supply and occupies 0.17 mm2 in a 0.18- μm CMOS process. The measured maximum signal-to-noise and distortion ratios at the two bandwidth settings are 50.5 and 52.5 dB, respectively. The corresponding third-order intermodulation intercept points (IIP3) are +28.2 and +30.8 dBm. Automatic tuning is used at the startup to counter process variations and set the bandwidth accurately.
Keywords :
CMOS analogue integrated circuits; active filters; elliptic filters; feedforward amplifiers; intermodulation; low-pass filters; operational amplifiers; tuning; .signal-to-noise ratio; CMOS process; automatic tuning; bandwidth 17 MHz; bandwidth 8.5 MHz; current-efficient feedforward-compensated opamps; distortion ratio; elliptic low-pass filter; feedforward current injection; high-IIP3 third-order elliptic filter; low-distortion active filter; operational amplifier; power 1.8 mW; size 0.18 micron; summing amplifier; third-order intermodulation intercept point; voltage 1.8 V; Bandwidth; Feedforward neural networks; Gain; Signal to noise ratio; Solid state circuits; Tuning; Automatic tuning; continuous-time filters; elliptic filters; feedforward compensation;
Journal_Title :
Circuits and Systems II: Express Briefs, IEEE Transactions on
DOI :
10.1109/TCSII.2011.2124571
