Ofcc Based Shadow Filter

An electronic filter is a linear two-port network, which is used for the purposes of frequency-selection or inversely frequency-rejection over a specified frequency range. Such networks ideally possess a frequency band over which the magnitude of transmission is unity (the filter passband) and a region where it is zero (the filter stopband) (Sedra & Smith, 2004) . The filter characteristics such as characteristic frequency (w ), Bandwidth (w /Q ), and 0 0 0 Quality Factor (Q ) can be electronically configured by 0 generally changing the value of the passive components depending upon the specific application for which the filter is to be used. In modern industry, the transceivers are held to a standard of receiving several standards simultaneously by optimizing the overall architecture such that parameters can be modified in order to adapt to each standard. Such a receiver is of great interest, because it will lead to important savings: reduction of size, price, complexity, consumption, etc. The configuration of the receiver is currently carried out By in the digital domain and at low frequency in the analog domain. However, to fully benefit from the DSP, it is desirable that this treatment is carried out at higher frequencies as close to the antenna as possible (Lakys & Fabre, 2012). Such architectures simply require reconfigurable analog elements, although design and implementation of reconfigurable filters over a wide range of frequencies remains a nuanced task (Lakys & Fabre, 2012). Such a new class of configurable second order filters were introduced in (Lakys & Fabre, 2010a; Roy, 2010) termed as shadow filters. In these filters, an external gain block (amplifier) is added in the feedback path and the characteristics of the resulting filter can be configured by controlling the gain (A) of the amplifier from low to high values (theoretically zero to infinity) (Roy, 2010). This class of th filters was further extended and generalized to n order filter in (Lakys & Fabre, 2010) along with generalized formula of characteristic frequency with respect to the filter order and gain of external amplifier. In literature, a limited number of topologies of shadow filters ABSTRACT This paper proposes an Operational Floating Current Conveyor (OFCC) based shadow filter configuration. The operation of the filter is based on modifying filter performance parameters with the help of gain of active block. This flexibility makes it attractive in comparison to a design, where similar control is achieved by changing values of relatively larger number of components. The proposed filter uses four active blocks (OFCCs), two grounded capacitors, and four grounded resistors and helps achieve low pass controlled low pass, high pass and band pass response. The use of grounded passive components makes proposed configuration, attractive from integrated circuit realization viewpoint. The functionality of the proposed circuit is demonstrated through SPICE simulations using the 0.5 m CMOS process model of MOSIS (AGILENT). The proposed circuit can be readily used in today's multi-standard transceivers in the IF stage for the implementation of frequency agile filters, which offer higher configurability to the transceiver chain and the analog front-end towards various standards of the ever changing industry demands.