Low-component-count current-mode Universal Filter based on active-only Lossy and Lossless Integrators Montri Somdunyakanok 1 , Krit Angkeaw 2 , Pipat Prommee 3 and Montree Kumngern 3 1 Electrical Engineering Department, Faculty of Engineering, Siam University, Bangkok 10160, Thailand. 2 Instrumentation and Electronics Engineering Department, Faculty of Engineering King Mongkut’s University of Technology North Bangkok, Bangkok 10800, Thailand. 3 Faculty of Engineering and Research Center for Communication and Information Technology King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand. Tel: 66-2326-4238, 66-2326-4242, Fax:66-2326-4554, Email: pipat@telecom.kmitl.ac.th Abstract— An universal current-mode active-only filter using the biquadratic transfer function is proposed. The proposed circuit is realized by lossy and lossless integrators with minimize active components count without external passive elements. The different kinds of filter functions as lowpass, highpass, bandpass and band-reject response can be obtained without changing circuit topology. The proposed circuit implementation is realized by using MOS transistors, CMOS MO-OTAs, and CMOS OPAMPs. The parameters ω P can be tuned electronically through adjusting the transconductance gains of the OTA or electronic resistor power supplies. The simulation results are given by PSpice. Keywords: Active-only, Filter, Lossy integrator, Tunable I. INTRODUCTION The high performance analog filter is much attractive for presently design in current-mode approach. There are many benefits larger than a voltage-mode counterpart as well as simply to summation and subtraction of their nodes, no need impedance matching. The previous works have been presented the various current-mode filters. Current follower (CF) [1], Current conveyor (CCII) [2], Operational Transcon-ductance Amplifier: OTA [3] have been constructed as the current-mode filters but they used external passive element or grounded capacitor as well. A biquadratic function transfer function is a well known method for realization of active filter. This multi-functions filter can be also obtained using this method. The open-loop gain bandwidth product (GBW) of OpAmp (OA) is familiar factor that is an operation bandwidth as an integrator. The OTA can be co-operated with OA for high frequency and suitable for further integration forms without passive components. Many papers introduced current-mode [5-7] and voltage-mode [8- 9] but some performances have been limited and also many components needed. Consider the previous active-only current-mode filters [5-6] used 2 OAs and 3 OTAs, the frequency response has been non-linearity controlled. Another paper enjoys linear controlled for frequency response but many components, 2 OAs and 5 OTAs are needed. This paper proposes a reduce components configuration of current-mode active-only filter based on a lossy and a lossless integrators loop. The 2 OAs and 2 MO-OTAs is used for a proposed circuit therefore, overall transistors are more reduced. The good benefits of electronically controlled and multi-function filters without changing circuit topology can be obtained. II. THEORY AND PRINCIPLE The biquadratic functions are familiar that related for the particular filter functions. The low-pass biquadratic function as shown Eq.(1) is used for an initial function for this paper. ( ) () 0 1 2 0 1 2 a sa s a s V s V + + = (1) Rearrangement of Eq.(1) in term of integrators. () () () ( ) s a s a s V s V s V 1 1 0 2 1 2 ⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + − = (2) From Eq.(2), the block diagram can be written by a lossy and a lossless integrators as shown in Fig.1. s 1 1 V 2 V 1 0 a s a + Σ Fig.1 Lossy and Lossless integrators loop block diagram A. Proportional Circuit Proportional or voltage-gain circuit [10] which used in this paper consists of an OTA and an electronic resistor as shown in Fig. 2. The transresistance of the electronic resistor circuit can be expressed in Eq.(3)