Abstract
In this paper, a new BJT based configuration for providing first order current mode high-pass, low-pass and all-pass filter responses from the same configuration is suggested. The proposed circuit called as a universal filter possesses some important advantages such as consisting of low component count BJT and a grounded capacitor, having electronic tunability property of its pole frequency and having electronic controllability feature of filter types. The suggested circuit does not suffer from disadvantages of use of the resistors. Moreover, as an application, second order band-pass filter is also obtained by cascading two proposed filter structure. Simulations by means of PSpice program are accomplished to demonstrate the performance and effectiveness of the developed first-order universal filter. Approximately more than 1 decade tunability range is achieved. Ill. 7, bibl. 14, tabl. 3 (in English; abstracts in English and Lithuanian). http://dx.doi.org/10.5755/j01.eee.112.6.448
Highlights
In the last two decades, current-mode (CM) circuits have received more attention
This paper presents an electronically tunable CM first order universal filter employing only a grounded capacitor and fewer BJTs [11] when compared with previously published ones
It is offers economic reasons to use of this circuit which have ability of electronically controllability since same manufactured circuit can be used for many purpose
Summary
In the last two decades, current-mode (CM) circuits have received more attention. These types of circuits offer many advantages such as wider bandwidth, bigger dynamic range, better linearity and more IC suitability when compared with voltage mode (VM) topologies [1, 2]. Step of designing first order filter is mapping on coefficients of generalized first order filter transfer function given in (1) to obtain appropriate system equations to realize function by using BJTs and a grounded capacitor. Both of two equations have scaling terms multiplied with input current As mentioned above, these terms consists of numerator’s coefficients of transfer function can be controlled by tuning some dc current sources. These terms consists of numerator’s coefficients of transfer function can be controlled by tuning some dc current sources It means that type of first order filter can be selected electronically. The expression of is given clearly in (9) This current which is key aspect of design consist of two constant terms, , cut off frequency, , the value of capacitor, and one time varying term, , the value of node voltage. Cut off frequency of proposed first order filter is given in (10):
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