A 2 V 0.25 /spl mu/m CMOS 250 MHz fully-differential seventh-order equiripple linear phase LF filter

A fully-differential seventh-order 0.05/spl deg/ equiripple linear phase low-pass filter based on multiple loop feedback (MLF) leapfrog (LF) topology is presented for read/write channels. The filter is designed and simulated with a fully balanced, highly linear operational transconductance amplifier (OTA). The proposed OTA contains two complementary differential cross-coupled input pairs and a pair of regulated cascode outputs in order to achieve both low-distortion and wide dynamic range in high-frequency operation. Simulations in 0.25 /spl mu/m CMOS show that the cutoff frequency of the low pass filter without and with gain boost ranges from 50 to 150 MHz and 65 to 250 MHz respectively, dynamic-range is over 65 dB and total harmonic distortion is less than 40 dB. The group delay ripple is less than 5% for frequencies up to 1.5 times the cutoff frequency, and for a 2-volt power supply, the maximum power consumption is 216 mW.