A CMOS 100 MHz continuous-time seventh order 0.05° equiripple linear phase leapfrog multiple loop feedback Gm-C filter
A novel 100 MHz CMOS Gm-C seventh-order 0.05° equiripple linear phase low-pass multiple loop feedback (MLF) filter based on leapfrog (LF) topology is presented. The filter is implemented using a fully-differential linear, high performance operational transconductance amplifier (OTA) based on cross-coupled pairs. PSpice simulations in a standard TSMC 0.25 μm CMOS process and with a single 5 V power supply have shown that the cut-off frequency of the filter without and with gain boost ranges from 8-32 MHz and 15-100 MHz, respectively. With gain boost, total harmonic distortion (THD) for a differential input voltage Vid of 315 mVpp at 1 MHz is less than -40 dB, dynamic range at 1% THD is over 55 dB, output noise with bandwidth 500 MHz is only 300 μVRMS, and power consumption is 322 mW.