Schematic Design of CBJT Fast Operational Amplifiers with Complementary Input Differential Stage

The authors have investigated the schematic design of a CBJT fast operational amplifier (OA) with a dualinput-stage. To increase the slew rate (SR), a differentiating transient correction sub-circuit has been introduced in the structure of this input stage. To improve the OA’s precision (reducing the off-set voltage’s systematic constituent - $\mathrm{V}_{\text {off-set }}$), the structure of two complementary reference current sources based on Wilson’s current mirrors is recommended, which provide high identity of the output currents. The parametric compensation’s methods of $V_{\text {off-set }}$ are considered on the example of OA’s three modifications with Wilson current mirrors, as well as OAs with a typical buffer amplifier on complementary bipolar transistors. Simulation results of the OA’s in the LTspice software environment are presented, showing that the SR of the CBJT OA’s for different static current levels of the differential stage’s common emitter circuit (up $16 \mu \mathrm{A}$ to 1.6 mA) improves from $16 \mathrm{~V} / \mu \mathrm{s}$ to $5100 \mathrm{~V} / \mu \mathrm{s}$. The element base of the presented schematic technology can also be made on the basis of SiGe technologies, as well as on wide band gap semiconductors ($\mathrm{SiC}, \mathrm{GaN}$, GaAs) for the purpose of designing high-temperature OAs. Moreover, the element base should combine complementary bipolar and/or CMOS field-effect transistors authorized for use in such process technology.