GaAs Operational Amplifier without Current Mirrors with Offset Voltage’s Systematic Component Compensation Circuit

The universal functional units of modern analog-to-digital signal processing systems, namely the operational amplifier architecture (Op Amp), which can be further realized on wide band gap semiconductors, is considered. The Op Amp input stage is made of GaAs pnp-BJTs, which provides a relatively low level of offset voltage’s systematic component and an increased slope of the mentioned input stage gain. A parametric compensation circuit offset voltage’s systematic component ($\mathrm{V}_{\mathrm{OS} 1}$) is introduced into the circuit presented in the article Op Amp, which minimizes the influence of the base current amplification factors of GaAs pnp-BJTs, which has a positive effect on reducing the value of $\mathbf{V}_{\text {oSI }}$. The prospectivity of cascode inclusion of JFETs with ntype channel in the reference current sources in the input and intermediate stages is shown. Computer modeling performed in LTSpice environment shows that $\mathrm{V}_{\text {OS1 }}$ is in the range of $1 \div 300 \mu \mathrm{V}$. The operational amplifier considered by the authors is recommended for operation with low impedance signal sources.