A new frequency agile filter structure employing CDTA for positioning systems and secure communications

Abstract

Multi-standard transceivers are more useful than the other classical transceivers. The flexibility of the multi-standard transceivers allow all pre-defined protocols to sense without redesign the transceiver in the RF front end. Multiple standard transceivers are used not only global markets but also military applications. Frequency agile filter is one of the basis element of multi-standard transceivers and some encryption techniques as frequency hopping spread spectrum (FHSS), DHSS. Some military applications (HAVE QUICK, SINCGARS, etc.) benefit from FHSS and direct-sequence spread spectrum to encode secret information by modulating different and arbitrary carriers. Such a technique needs frequency agile filters to detect signals modulated with different carriers. There are several methods to design frequency agile filters. In this work, current differencing trans-conductance amplifier (CDTA) is used for frequency agile filter design. Current differencing trans-conductance amplifier (CDTA) can be considerable alternative building block of current mode operational amplifiers. The circuit description of CDTA is very suitable to design analog filters by using only capacitors. A new reconfigurable filter employing CDTAs for analog signal processing is proposed in this paper. The filter structure consists of CDTAs as active element and only two capacitors as passive element. The designed filter operating range is applicable for different GPS protocols to implement on the same chip, SINCGARS (single channel ground and airborne radio system) and filtering IF signals. The filter is designed with AMS 0.18 A mu m technology. The filter performance is tested and verified by simulations with Cadence environment.