A Novel ±0.5V Ultra High Current Drive and Output Voltage Headroom Current Output Stage with Very High Output Impedance

A novel ultra-high compliance, low power, very accurate and high output impedance current output stage (COS) with extremely high output current drive capability is proposed in this paper. The principle of operation of this unique structure is discussed, its most important formulas are derived and its outstanding performance is verified by HSPICE simulation in TSMC 0.18µm CMOS, BSIM3, and Level49 technology. This deliberately composed structure utilizes a well combination (for a mutual auto control action) of negative and positive feedbacks to achieve ever demanded merits such as very low power of 150µW, ultra high ratio of 3000 for output current over the bias current (which is selected to be 0.5µA) at low THD of -20dB and very high output impedance of 5GΩ with power supplies of ±0.5V when operating at class AB mode. Simulation results with ±0.5V power supply shows an absolute output voltage dynamic range of 0.9V which interestingly provides the highest yet reported output voltage compliance for Current mode building blocks implemented by regular CMOS technology. Full process, voltage, and temperature variation (PVT) analysis of the circuit is also investigated in order to approve the well robustness of the structure. The transient stepwise response is also done to verify the proposed COS stability.