Current-mode filter in 65nm CMOS for a software-radio application

For the transmit path of a software radio defined system a 3rd-order current-mode filter in 65nm CMOS is presented. This filter consists of a 1st-order current-mode filter where a capacitance multiplication technique is applied. With this technique the needed capacitance is decreased by a factor of 2. The 2nd-order filter consists of an active gm-RC filter where the output voltage is also converted into a current. The filter has a switchable cut-off frequency of 1MHz and 4MHz, the current consumption is 5.26mA at V DD =1.2V and for an input current of 340μA the THD is 1%.