A very wideband fully balanced active RC polyphase filter based on CMOS inverters in 0.18μm CMOS technology

A very wideband active RC polyphase filter(RCPF) is presented. A unit active RCPF section structure is an ordinary RCPF followed by opamps with parallel RC feedback. The cascaded sections allow zeros and poles to set independently, it can greatly reduce the element value spread. A six-stage active RCPF with a relative bandwidth of 100(=100 MHz/1 MHz) was fabricated by 0.18 μm CMOS with novel fully differential OTAs consisting only of CMOS inverters. Measured frequency responses closely matched simulated results.