A gain-controlled integrator technique for a 50 MHz, 100 mW, 0.4 /spl mu/m CMOS, 7th-order equiripple G/sub m/-C filter

This gain-controlled integrator technique generates high-precision, high-speed, low-voltage G/sub m/-C filters. Cut-off frequency (fc) must be tunable between 50 - 100MHz. Group delay variation ±5% of l/fc over the full fc range is required for linear phase response. A 7th-order 0.05° equiripple filter with three quadratic sections and a one-pole low-pass section is used for its inherently low group delay variation. For precise equiripple filter characteristics, the quality factor (Q) and pole-frequency (fp) must coincide with their specified values over the full fc variable range.