CMOS 4th-order gm-c low-pass filter with wide tuning range in high frequency

Designed and implemented a CMOS continuous time 4th-order gm-c low-pass filter with frequency tunable. Nauta's transconductor is applied for absence of internal node, feasibly for high frequency wide band operation. Biquadratic architecture is adopted because of its advantages in design and layout. The corner frequency of the filter is tuned by constant-gm method. The filter is implemented in CMOS 0.5¿ double poly triple metal mixed signal process. The layout area is 330 um*140 ¿m.The circuit consumes 4.3 mA through a 3.3V power supply with a corner frequency tunable range from 15 MHz to 95 MHz in post layout simulation.