M.Sc Thesis:

Subject: New Realizations of Analog/Digital and Digital/Analog Converters Using Operational Transconductance Amplifiers (OTAs).

Abstract: In this thesis, two new methods for realizing of Digital to Analog (D/A) and Analog to Digital (A/D) converters using operational transconductance amplifiers (OTAs) have been presented. The OTA is an active circuit with two high impedance input ports and a controlled output current source. The high frequency performance of the OTA is noteworthy and quite advantageous according to operational amplifier (Op-Amp). The proposed DACs and ADCs (8-10-12 and 16 bit) use only active elements and can be used in high frequency applications (up to 100Mhz). The dynamic performance of the converters was also tested.

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Ph.D Thesis:

Subject: New Possibilities In Current-Mode Circuits Using Current Controlled Conveyor.

Abstract: In this thesis, at first a detail study in bipolar realization of the current controlled conveyor (CCCII) is performed. The DC and AC characteristics of the bipolar CCCII are extracted and non-ideality parameters of the CCCII are given. Also the bipolar realization of the CCCII is slightly modified which results in a wider tuning range. Then to illustrate the usefulness of the CCCII many new CCCII-based applications are proposed. These are current-mode single-input three-output universal filter, first order all-pass filters, floating inductance simulator and oscillator.

Moreover in order to take the advantages of the BiCMOS technology such as requiring small silicon area and high frequency performance together with high input resistance a BiCMOS realization for the CCCII is presented. The AC and DC characteristics of the proposed realization are given and the circuit is tested on a bandpass filter.

The most important section of the thesis is the investigation of the dominant non-ideality effects of the CCCII in resonant angular frequency and quality factor of the second order bandpass and lowpass filter constructed with single CCCII. The graphics of the normalized resonant angular frequency and quality factor of these filters are extracted and simplified formulas for calculating these parameters are given. The effects of the non-idealities on the stability and sensitivities of the proposed filters are investigated in details.