Generation of complex impedance for complex filter design using fully balanced current conveyors

Abstract

In this paper a complex filter is presented where the shift in the frequency is obtained using a linear frequency transformation. The linear frequency transformation in the proposed design is implemented using a complex impedance. A complex impedance is also proposed in this paper using a Fully Balanced Second Generation Current Conveyor (FBCCII). The FBCCII design used in this paper consumes $$84\,\upmu \hbox {W}$$ of power and has an open loop gain of 47.83 dB with $$62.9^\circ$$ of phase margin at 39.8 MHz unity gain bandwidth. A low power 3rd order complex filter is designed by linear frequency transformation at 40 MHz center frequency. The proposed complex filter achieves a bandwidth of 9 MHz with an image rejection ratio of 45 dB. The design consumes 1.5 mW of power and has a group delay of 12.5 ns. The figure of merit of the proposed filter is 0.007 fJ with a SFDR of 63.9 dB. The output noise of the design at 40 MHz center frequency is $$45.86\,\hbox {nV}/\sqrt{\hbox {Hz}}$$ and integrated Input Referred noise is $$600\,\upmu \hbox {V}$$ . The design is simulated using a 180 nm CMOS technology with a supply voltage of $$\pm \,0.5\,\hbox {V}$$ . The circuit’s efficacy is verified and supported by PVT and post layout simulations. The area of the layout of the proposed design is $$0.624\,\hbox {mm}^{2}$$ (i.e. $$260\,\upmu \hbox {m} \times \,240\,\upmu \hbox {m}$$ ).