A Simple Transimpedance-mode Instrumentation Amplifier Based on Only Single Second Generation Voltage Conveyor (VCII)

In this article, a simple transimpedance-mode instrumentation amplifier (TIA) is described. To enlarge the signals from current source transducers, a TIA is a better choice since the input current can be directly processed without conversion to voltage signal. The circuit implementation consists of only 1 second generation voltage conveyors (VCII) and 1 external grounded resistor. Its differential input current is amplified and sent to be an output voltage without an additional voltage buffer. It offers a high differential transimpedance-mode gain and common-mode rejection ratio (CMRR). Its transimpedance gain can be widely adjusted by the external grounded resistor. Consequently, it can be easily adapted to offer electronic controllability by using an electronic resistor replacing to the grounded resistor to be used in automatic or microcontroller-based control systems. Several work-abilities of the proposed TIA are revealed via PSpice simulation using TSMC 0.18µm technology CMOS transistors. The CMRR of 35dB with the -3dB bandwidth of 46.823MHz is obtained. The maximum total harmonic distortion (THD) of output voltage is 1.8% for frequency of 10MHz and 0.14% for 500µAp of input current. Total power consumption of the proposed circuit is 0.303mW at ±1.2V supply voltages.