A Novel CMOS Realization of the Differential Input Balanced Output Current Operational Amplifier and its Applications

Abstract

In this paper a new realization of the differential input balanced output current opamp is proposed, operating with ±1.5 V supplies. Its architecture is based on the use of current inverters to sense the input currents while providing a very low input resistance, 23 . The opamp provides a maximum output swing of 700 µA, with an input offset current of 3.5 nA. The differential gain achieved is 65.5 dB, and the differential structure adopted in the design provided a high CMRR, 89.5 dB, the proposed circuit is compared to other realizations with single and differential inputs. The applications of the current opamp are exploited some new applications are presented such as: MOSFET-C integrators, full non-linearity cancellation for MOS transistors, and finally a digitally tuned current-mode variable gain amplifier, which has a gain tuning range of 25 dB with a 0.05 dB step.

New Voltage-Mode All-pass Filter Topology Employing Single Current Operational Amplifier

“…Also, the current differencing and internally grounded inputs of COA make it possible to implement the COA-based circuits with MOS-C realization (Kılınç et al, 2005). An ideal COA is mainly an infinite gain current controlled current source, but in practical cases the gain becomes a function in frequency exhibiting a single pole response, this will guarantee the stability of the closed loop systems (Youssef and Soliman, 2005).…”

“…The current operational amplifier (COA) is still emerging as one of the most important currentmode active building blocks and it is the exact current-mode dual of the voltage-mode operational amplifier (VOA). There are some CMOS implementations of COA and COA based filter circuits in the literature (Kılınç and Çam, 2003;Altun and Kuntman,2007 ;Yamaçlı and Kuntman, 2005;Youssef and Soliman, 2005;Kılınç and Çam, 2004;Altun and Kuntman, 2006;Kılınç et al, 2005;Altun, 2007;Cheng and Wang, 1997;Mucha, 1995;Uygur and Kuntman, 2004). Among the reported filters, none of them is employing current conveyor based COA.…”

Realizations of CMOS fully differential current followers/amplifiers

“…This can be achieved easily by proper sizing of the current mirroring transistors. This concept was used in [3] as a differential input single output circuit to realize the input stage for a COA. Here this idea is extended to fully differential outputs and its common-mode rejection is analytically explored.…”

“…A current amplifier has a general current gain A i =b. The current operational amplifier (COA) is obtained when current transfer A i goes to infinity; see for example [1]- [3]. Unlike COAs, CFs/CAs can be used in open loop circuit topologies.…”

Current‐mode dual‐output ICCII‐based tunable universal biquadratic filter with low‐input and high‐output impedances

“…The proposed circuit enjoys the following advantages: (1) employs three active components, (2) employs only grounded passive components, (3) can simultaneously realize three basic filter responses with single input and three outputs all at high impedance outputs, (4) can realize LP, BP, HP, BR and AP filter responses by selecting different three input current signals, (5) has no capacitors bringing extra poles degrading its high-frequency performance, (6) has both low-input and high-output impedances, thus it can be easily cascaded other CM topologies, (7) requires no inverting type current input signals, (8) requires no components matching chosen conditions, (9) has orthogonal controllability of the characteristic parameters o o and Q and (10) has low active and passive components sensitivities. Either single-input three-output or three-input two-output CM biquadratic filter can work in the same configuration.…”