REALIZATION OF DXCCII BASED HALF WAVE AND FULL WAVE RECTIFIER

Abstract

Rectification is a demanding aspect when it comes to electronic equipment. The demand of low supply voltage and high speed devices has increased the demand of such rectifiers which can process low amplitude signals with high efficiency and can operate at high frequencies. Such rectifiers are called as the precision rectifiers which are used for signal processing, measurement and control of the low level signals. In the past operational amplifiers have been used to develop the precision rectifiers but they failed to operate at high frequencies due to their slew rate limitations. They also needed passive devices such as diodes and matching resistors which offered difficulties in their integration. The employment of current mode techniques either by using current conveyors or by creating dedicated CMOS circuits have fruitfully resolved the conventional limitations by providing much enhanced performance of precision rectifiers. Concerned about the above mentioned issues, three newly proposed circuits are presented to serve the applications of precision rectification. Each circuit employs single Dual-X Second Generation Current Conveyor (DXCCII) as the active building block and uses one or two NMOS transistors for the switching purposes. The first two proposed circuits are voltage mode precision half wave rectifiers. The first proposed precision half wave rectifier rectifies the positive half cycles of the input AC (Alternating Current) voltage signal while the second proposed precision half wave rectifier rectifies the negative half cycles of the input AC voltage signal. The third proposed circuit is a voltage mode precision full wave rectifier that provides the full wave rectification of the input AC voltage signal. Further two voltage mode digital modulators have been proposed i.e. Binary Amplitude Shift Keying (BASK) and Binary Phase Shift Keying (BPSK). BASK uses one DXCCII and one NMOS transistor. BPSK uses one DXCCII, one NMOS transistor and one PMOS transistor.

All the above proposed circuits have the advantage of having proper input impedance and use of grounded resistor. The rectifiers provide additional advantage of using no diodes for rectification, rather NMOS transistors are used. All the proposed circuits have been simulated with SPICE using 0.35µm CMOS technology parameters. The supply voltage of ±1.8V is used. Much satisfactory results have been obtained with all the proposed circuits.