Resistorless Reconfigurable nth-Order Filter Based on DPCDTA for Multi-mode Filtering Applications

Abstract

This paper presents a new topology for realizing current-mode reconfigurable nth-order filter for multi-mode wireless communication equipments, which is based on a new active device, namely digitally programmable current differencing transconductance amplifier (DPCDTA). The proposed filter is resistorless, and it employs n DPCDTAs and n grounded capacitors with one input and one output terminals. The signal path of the filter does not contain any switches, and wide tuning coefficient of the filter is implemented using programmable current division network with zero standby power consumption in the DPCDTA. Also, the proposed topology exhibits broader programmable features to accommodate wide range of selectivity requirements, which can be used as the most compatible structure for fieldprogrammable analog array and very suitable for multi-mode filtering applications. The programming ability of variable filter orders from first to fourth providing low-pass, highpass, and band-pass responses, and programming ability of variable cutoff frequencies from 1.14 to 11.75 MHz are given as application examples. The performance of the circuits have been verified and evaluated through post-layout simulations using Cadence IC5141 with GlobalFoundries'0.18 μm CMOS process.