IMPLEMENTATION OF ANALOG SIGNAL PROCESSING CIRCUITS USING EXCCII

Abstract

Analog signal processing (ASP) is any type of signal processing conducted on continuous analog signals by some analog means as set of continuous values (as opposed to the discrete digital Signal Processing (DSP) where the signal processing is carried out by a digital process). DSP suffers of fundamental drawbacks, such as high cost analog-digital conversion, high power consumption and poor performance at high frequencies. To overcome these drawbacks, ASP is preferred.

Current mode (CM) blocks offers advantages over voltage mode (VM) blocks, such as performance improvement, low power consumption, controlled gain without feedback components, better linearity and improved bandwidth. This gives the motivation to use CM block to implement various ASP applications and to review already existing literatures available using CM blocks. Current conveyor is used as it is a high-performance active element and it ensures high accuracy, wide bandwidth and exceptionally high slew rates combined with low voltage and low power implementations under small or large signal conditions. As compared to op-amp based circuits, the conveyor based circuits offers a higher gain-bandwidth product which makes it an ideal choice for modern applications in analog signal processing. Extra X- second generation current conveyor (EXCCII) is one of the new emerging CM block. In the process, an EXCCII with buffered output is used which is a modified second generation current conveyor that provides an extra input terminal. The block EXCCII has been verified and its applications on electronic functions like amplitude shift keying (ASK), binary phase shift keying (BPSK), current mode half wave and full wave rectifiers have also been verified. All pass filter, current mode universal and biquad filter have been explored.

From literature survey done it is found that, instrumentation amplifier, oscillators, multivibrators have not been explored using EXCCII. This inspires me to do work on applications mentioned above. The new topology of instrumentation amplifier (IA) using EXCCII is proposed and analyzed which is working in current mode (CM) and has high input impedance, low output impedance, high differential mode gain and high CMRR. Another application using EXCCII is mixed mode three phase oscillator may also be proposed and is under analysis. A feedback scheme consisting of two lossy integrators followed by a lossless inverting integrator is employed to obtain three voltage-mode and three current-mode sinusoidal signals simultaneously. The functionality of the two proposed circuits are analyzed through PSPICE simulation using 250 nm (0.25µm) TSMC technology parameters.