Programmable gain amplifier using operational floating current conveyors

This paper presents new operational floating current conveyor (OFCC) based Programmable Gain Amplifier (PGA). It operates in trans-impedance mode i.e. it receives current signal as input and provides voltage as output. It uses four blocks - a current amplifier, digitally controlled trans-impedance amplifier, digitally controlled R-2R ladder network and a voltage buffer. First block amplifies input signal. Second and third blocks of proposed PGA provide control over coarse and fine gain through bits (B5-B0) and a total of 60 different gain values are possible through the arrangement. The last block provides output at low impedance thereby avoiding need of impedance matching circuit. The operation of the proposal has been verified through SPICE simulations using 0.5 µm technology model parameters from MOSIS (AGILENT). The simulated variable gain range is found to be 56.76 dBΩ to 95.84 dBΩ. The total power dissipation is 3.13 mW under maximum gain settings. The equivalent input referred noise is found to be 6.9 pA/√Hz. Experimental verification of proposed PGA is also done by bread boarding the entire circuit. The measured results are found to be in close agreement with the theoretical and simulated values.