An Improved DDCCTA Toward its Application in Different Wave-Function and PWM Generation

Differential difference current conveyor transconductance amplifier (DDCCTA) is an important building block for current mode circuits. However, the existing DDCCTA circuit suffers from a current error, low tolerance to bias voltage deviation, and requirement of additional circuit for bias current. Hence, a new DDCCTA circuit alleviating these shortfalls is proposed using only two variants of MOS parameters. The proposed DDCCTA operates over a bandwidth of 500 MHz. It delivers more than 117% larger linear operational range and offers larger performance stability than the existing DDCCTA circuit. Further, it has been used to generate sinusoidal, square, and triangular waveforms. However, investigation shows that it is quite challenging to generate all these waves along with a PWM using a single DDCCTA block. Therefore, a new block termed as DDCC-X-TA-X is proposed to generate all the said waves and a PWM simultaneously from a single active block and using only a few passive components. Practical emulation of the circuit, using AD844 and CA3080, also confirms its operation. Pre- and post-layout simulations of this new block have also been done. Monte Carlo simulation and PVT analyses depict that the circuit operation is quite stable to the fabrication imperfection originated mismatches in transistor parameters and temperature variations.