100-MHz monolithic low-pass filters with transmission zeros using NIC integrators

Abstract

A monolithic method of implementing VHF filters with transmission zeros is presented. The transmission zeros are obtained using a modified leapfrog simulation method realized without floating capacitors that does not require summing circuits inside the feedback loops. The integrators used are balanced negative impedance converter (NIC) integrators with grounded capacitors, which do not require p-n-p transistors and are suited for low-voltage applications. A low-pass filter with a cutoff frequency of 100 MHz and with a transmission zero at 166 MHz designed and built in an integrated circuit form showed good results, confirming the feasibility of the method. >