A low power 44-300 MHz programmable active-RC filter in 0.18 μm CMOS

We present a widely programmable fifth order Chebyshev opamp-RC ladder filter whose 3 dB bandwidth is digitally tunable over a 7X range, from 44-300 MHz. The opamp uses feed-forward compensation to achieve high DC gain and wide bandwidth with reduced bias currents. The principle of "constant capacitance scaling" is used to maintain the shape of the filter response when the bandwidth is changed by a large factor. The filter consumes 36 mW from a 1.8 V supply and has a dynamic range of 56.6 dB.