Composite operational amplifiers: Generation and finite-gain applications

A practical near constant bandwidth amplifier

“…The proposed circuit can also be considered as a special case of the circuit in Figure 4 of [14] with R L = ∞ or more importantly identified as C2OA-3 in Figure 3(c) of [18] and reproduced here Figure 4 to various gains and two values ofˆ using two LT1364 opamps. Solid line isˆ = 0 (Figure 1(a)) and the dashed line iŝ = 8.2.…”

“…Finally, the circuit can also be viewed as a new type of composite amplifier. These have been used in the past to improve the performance of active filters [12][13][14][15], oscillators [16], increase loop gain or provide improved phase accuracy [8,17] using two, three or four opamps [18,19]. However, to the best of the authors knowledge they have never used to obtain a near constant bandwidth feature.…”

Versatile composite amplifier configuration

“…Composite amplifiers comprising two or more amplifying elements are generally designed to achieve performances unachievable by a single device (Apex Microtechnology, 2012;Franco, 2002;Gerstenhaber & Tran, 2002;Mikhael & Michael, 1987;OA-07 Current Feedback, 2002;Redmayne, 2002;Stofka, 2008;Williams, 1986). These modules usually involve the operational amplifier (OPA), and they have been used to increase loop gain (Franco, 2002), phase accuracy (Graeme, 1993;Wong, 1987), bandwidth (Geiger, 1977;Stofka, 2008), noise reduction (Schmid, 1994) and bandwidth constancy (Maundy, Gift, & Westwick, 2009) in amplifier systems.…”

“…In the section that follows, we briefly review the conventional composite amplifier (CCA) and present its theory of operation which was not previously presented in Williams (1986) or Mikhael and Michael (1987) or Franco (2002).…”

A comparison of two actively compensated active-RC filters

“…Subsequently, another scheme was suggested by Schaumann in [5] for improving the same SAB. Schaumann's scheme uses the composite amplifier C02A-4 of [6]. A modified form improved the performance of the filter circuit of [5] by halving the u p and Qp sensitivities with respect to the GB products in comparison to Schaumann's design [i'].…”