High CMRR and low THD current-mode instrumentation amplifier using current inversion technique

The current-mode instrumentation amplifier based on second-generation current conveyors (CCII) offers many benefits over conventional instrumentation amplifier architectures. It does not need any matched components to achieve high CMRR and its bandwidth is not gain-bandwidth product limited. Therefore, a wideband CMOS current conveyor has been used in this structure. HSPICE simulations have shown that its performance is quite satisfactory for wideband current-mode signal processing. Furthermore, CMRR enhancement technique of current-mode instrumentation amplifiers is discussed. In addition, composite conveyor techniques which improve the instrumentation amplifier performance are presented. The new simulated instrumentation amplifier provides approximately 44 dB of improvement on the high-frequency CMRR up to the 3-dB corner frequency and even higher. Also a THD of %0.6 has been achieved.