This paper presents operational floating current conveyor (OFCC) based single input four output current mode filter. It employs only three OFCCs and two grounded capacitors and resistors each. The MOS based grounded resistors implementation is used, which adds feature of electronic tunability to the filter parameters. The filter also enjoys low component spread and low sensitivity performance. The effect of finite transimpedance and parasites of OFCC on the proposed circuit is also analyzed. The functionality of the proposed circuit is demonstrated through SPICE simulations using 0.5 µm CMOS process model provided by MOSIS (AGILENT).
The development of current mode continuous time filters has received growing interest due to its applications in sampled data systems, communications, and control systems [
The circuit symbol of operational floating current conveyor (OFCC) [
Circuit symbol of OFCC.
CMOS schematic of OFCC [
In this section the implementation of OFCC based current mode singleinput fouroutput filter, as shown in Figure
Proposed OFCC based singleinput fouroutput current mode filter.
All the responses are characterized by pole frequency (
The proposed filter uses grounded resistors which can easily be implemented using the MOS based structure given in Figure
MOS realization of a resistor [
The sensitivity analysis of the proposed circuit is as follows:
In this section the effect of finite transimpedance gain of OFCC is considered and compensation is employed for high frequency applications. Ideally the transimpedance gain
The second group of nonidealities comes from parasites of OFCC comprising of resistances and capacitances connected in parallel at terminals
Proposed OFCC based current mode filter with parasites.
To verify the functionality of the proposed OFCC based current mode filter, SPICE simulations have been carried out using 0.5 µm CMOS process model provided by MOSIS (AGILENT) and CMOS schematic of Figure
Transistors aspect ratios of the circuit shown in Figure
Transistor 



50/1 

50/2.5 

20/2.5 

40/2.5 

100/2.5 
The simulations have been performed for a pole frequency of 1.59 MHz with component values as
Simulated low pass, band pass, and highpass responses.
Magnitude and phase plot for notch response.
Magnitude and phase plots for allpass response.
The orthogonal adjustment of
Bias voltages/resistor values for orthogonal adjustment of









1.310  −1.310  1  1.310  −1.310  1  1  1590 
0.869  −0.869  2  0.869  −0.869  2  1  800 
0.726  −0.726  5  0.726  −0.726  5  1  320 
0.711  −0.711  10  0.711  −0.711  10  1  160 
Bias voltages/resistor values for orthogonal adjustment of











1.310  −1.310  1  0.869  −0.869  2  0.1  0.2  0.5  800 
0.869  −0.869  2  0.869  −0.869  2  0.1  0.1  1  800 
0.869  −0.869  2  1.310  −1.310  1  0.2  0.1  2  800 
Tuning of
Tuning of
To study the time domain behavior of the proposed filter, an input sinusoidal signal of 500 KHz frequency and amplitude 2 µA is applied. The transient response for low pass output is shown in Figure
Transient response for low pass output.
(a) Transient response of input and output signals (b) Spectrum of input and output signals.
In this paper, a singleinput fouroutput current mode filter based on OFCC is presented. The circuit uses only three OFCCs, two grounded resistors, and two grounded capacitors. The low pass, band pass and notch responses are available at high impedance whereas highpass and all pass responses can be obtained by adding