A 5.5MHz CMOS Low-Pass Filter using a `Soft-Switched' Transconductor

A new transconductor has been used to implement a third-order 5.5MHz low-pass Bessel filter with extra notch. The filter was realised in 0.5 μm double poly N-well CMOS process. At a 3.3V supply voltage the filter dissipates 12mW and the dynamic range equals 62dB where the THD is-50dB for an input voltage of IVpp. The continuously tuneable transconductor is based on `soft-switching' of resistors. The converter performance is only determined by the first order characteristics of the transistor. Due to reduced sensitivity for the second order effects of the transistors the converter is well suitable in modern and future sub-micron CMOS processes.