A novel differential cascade circuit has been developed and investigated, implemented using a GaAs technology process that allows the use of nJFET and p-n-p bipolar transistors. Computer modeling of the proposed circuit solutions has been performed, incorporating nonlinear correction circuits for the transfer characteristics of the differential cascade, which increase the maximum slew rate (SR) of the operational amplifier (Op-Amp) by more than an order of magnitude. The simultaneous effect of nonlinear correction circuits and a transient-response differentiating circuit has been analyzed, enabling a further increase in SR (up to $4235 ~\mathrm{V} / \mu \mathrm{s}$). This paper is dedicated to the study of one of the most in-demand analog IP modules for embedded systems - a GaAs operational amplifier which, thanks to new circuit design solutions in the input stage, provides enhanced maximum slew rate values while maintaining low quiescent current and, consequently, reduced self-heating of the input transistors.

It is shown that one of the promising areas in the design of high-temperature operational amplifiers (Op-Amps) are GaAs circuit solutions based on an “folded” cascode. Circuit engineering methods for improving Op-Amp parameters of this class have been developed and investigated when implemented on GaAs nJFET and GaAs bipolar p-n-p transistors. Due to the original circuit design solutions, the systematic components of the zero offset voltage in the OpAmp are minimized due to the influence of the GaAs p-n-p BJT base currents and the asymmetry of the gate-drain JFET transistors of the input differential pair. Mathematical constraints have been obtained for the static mode of the OpAmp, in which the total zero offset voltage takes on minimal values. As an example, a computer simulation of one of the OpAmp circuits of the class in question was performed in the LTspice environment. The developed GaAs Op-Amp family is recommended for use in analog automation devices operating at elevated temperatures (up to 250 – 300 °C).

One of the factors determining the reliability of information systems is the accuracy of data processing results. The paper addresses the design challenges of spectrum limiters incorporated at the input and output of discrete-analog switched-capacitor filters (SCFs), which are essential for reducing aliasing errors and improving the reliability of analog information processing systems based on them. Possible frequency tuning options for the amplitude-frequency response of SCFs are demonstrated – by adjusting component parameters, pulse-width modulation of control pulses, and the switching frequency of electronic switches. A design methodology is proposed for analog anti‑aliasing filters that provide specified attenuation of additional spurious spectral components at the SCF output. MicroCap simulations indicate that a high-order Chebyshev low-pass filter (LPF) should be selected as the anti‑aliasing filter to achieve the required suppression of spurious passband frequencies. Experimental studies of a prototype of one of the developed SCFs using the Russian electronic components have shown a high degree of correlation between the measured SCF characteristics and the computer simulation results for the same characteristics.

A new class AB gallium arsenide differential stage circuit has been developed and investigated. It is implemented using a combined gallium arsenide process technology, which allows the use of only nJFET field-effect transistors and p-n-p bipolar transistors. Computer simulation results are presented, demonstrating the possibility of significantly improving the dynamic characteristics of operational amplifiers in the in highsignal mode based on the considered differential stage circuit. It has been established that the transfer characteristic of the considered differential stage has a quadratic dependence of the output current on the input differential voltage. The proposed differential stage construction method ensures an increased slew rate of up to $1000 \mathrm{V} / \mu \mathrm{s}$ in operational amplifiers with low static current consumption of the input differential stage and operation of its transistors in the range of up to $100-200 \mu \mathrm{A}$, which reduces their self-heating and expands the range of operating temperatures

A method for designing anti-aliasing filters for use in information and control systems is proposed. A distinctive feature of the filters under consideration is that their amplitude-frequency response has transmission zeros at critical (from the point of view of interference suppression) frequencies and a specified attenuation in the rest of the frequency range. This allows the use of the filters in question, both for the suppression of undesirable harmonics of the network (50 Hz and 100 Hz), and as spectrum limiters at the inputs of analog-to-digital converters and, in particular, at the inputs of discrete-analog filters made on switchable capacitors. It is shown that the found transfer function of the filter can be implemented on the basis of cascade or multi-loop structures, and the circuitry of such filters can be made on the basis of RC circuits and op-amps. The calculation of the parameters of the elements of the circuit diagrams of filters is carried out according to the coefficients of the specified transfer function. Cascade implementation is based on the principle of internal models, which ensures the greatest stability of the filter's critical frequencies.

The focus of this article is on a differential stage (DS) that is implemented on depletion-mode CMOS-transistors, which makes it possible to construct a circuit with improved characteristics compared to traditional solutions. This implementation enables the creation of a DS that operates in class AB mode with low static power consumption. This operating mode is particularly relevant for the design of low-power analog integrated circuits intended for use in portable and energy-efficient devices. The dependence has been identified using computer simulation that reflects the influence of the input differential voltage on the output DS’s currents. It is shown that the CMOS operational amplifier based on the classical dual-input-stage DS has a limited rate of output voltage rise due to current limitations of the input stage. The article also presents an operational amplifier circuit that increases the slew rate by more than 10 times. This approach holds promise for the development of high-speed CMOS operational amplifiers with low intrinsic heat dissipation.

Current mirrors introduce significant errors into the static and dynamic parameters (the systematic component of the zero offset voltage, attenuation factors of common-mode input signals, power supply rejection, slew rate in the mode of a large pulsed input signal, unity gain frequency, etc.) in classical operational amplifiers with direct coupling of cascades. A gallium-arsenide operational amplifier that does not contain current mirrors, as well as resistors that establish the static mode of gallium-arsenide field-effect and gallium-arsenide bipolar transistors is studied in the article. A promising gallium arsenide technological process, mastered by the Minsk Research Institute of Radio Materials, ensures the creation of only p-n-p BJT and nJFet transistors. The absence of n-p-n transistors creates problems in the construction of high-temperature gallium-arsenide operational amplifiers, which are in demand in a number of important branches of science and technology - space instrumentation, oil and gas, automobile and aviation industries. It is shown that the proposed circuit solutions minimize the systematic component of the zero offset voltage and can be recommended for practical use in analog interfaces designed to operate at elevated temperatures.

This paper considers the design of spectrum limiters connected at the input and output of switched-capacitor filters (SCF) used in modern monitoring and control systems (MCS). The installation of such filters is associated with the need to reduce the aliasing error during signal sampling at the SCF input and to minimize interference at actuator inputs. In the considered MCS, aliasing issues also arises at the analog-to-digital converter (ADC) input within the system architecture. This solution must be considered when designing ADC input filters based on SCF. The study investigates analog anti-aliasing filters (AAF) suitable for MCS applications. Algorithms and methods for data acquisition in the MCS input module from low-pass and bandpass SCFs are described. Control information output errors in MCS, which significantly impact system reliability, are examined. The research demonstrates that switched-capacitor filters (typically used at both system input and output) require an AAF at the SCF input and a low-pass filter at its output. For high ratios of SCF sampling frequency to the cutoff frequency of the input signals spectral density envelope, the the analog anti-aliasing filter order does not exceed one. As the SCF order increases, the AAF order increases correspondingly. The article emphasizes that AAFs, unlike SCFs, feature fixed parameters, leading to performance degradation when SCF settings are modified. Implementing analog anti-aliasing filter with controllable characteristics in the control system partially problemresolves this issue, but complicates the system tuning algorithm. The conclusion states that the using analog filters reduces the permissible range of SCF parameter variations and requires solving technological challenges in manufacturing AAFs with large nominal component values, which affects the performance characteristics of SCF.

Today, large language models are used as information support for solving a wide range of problems in science and technology. They are particularly effective in tasks where information is represented as text. The design of analog integrated circuits, including high-temperature operational amplifiers, is one such task. This paper develops a method for communicating with a large language model to improve the parameters of a basic prototype circuit. The work is demonstrated using the example of reducing the temperature coefficient of the input offset voltage of CMOS operational amplifiers in the range from -40 to 125°C. In this case, the verification of the intermediate results by computer simulation and graphical drawing of the schematic is done by a human. The proposed method has significant potential for application in the design of high-temperature integrated circuits.

The circuit design of a gallium arsenide operational amplifier (Op-Amp) implemented using GaAs nJFETs and GaAs p-n-p bipolar transistors through a combined technological process is considered. Results of mathematical and computer simulations of the Op-Amp are presented, showing that it has a voltage gain of over 90 dB and a systematic offset voltage component of less than $100 \mu \mathrm{~V}$. Due to the use of transistors on a wide-band semiconductor, the proposed circuit solutions are recommended for practical use in analog interfaces for operation at elevated temperatures.

High-speed operational amplifiers are widely used in quantum-optical systems and equipment for recording fast pulses. The high level of parameters of such products is ensured by the use of modern technological routes for manufacturing microcircuits containing complementary bipolar transistors with a high cutoff frequency and a low parasitic collector capacitance. These technological routes for the manufacture of microcircuits are not available in Russia and Belarus. In order to meet the existing needs of the domestic market for radio-electronic equipment, two operational amplifiers on an MN2KhA031 master slice array (MSA) with unified stages and the possibility of changing the parameters by selecting the resistance of the current-conducting resistors and the capacity of the balancing capacitor are presented. The circuit diagrams are described and the results of the circuit modeling of two products are presented: a high-speed operational amplifier OAmp9 with a gain bandwidth product of more than 600 MHz, an output voltage rise rate of over 400 V/μs with the static parameters corresponding to general-purpose operational amplifier applications, and a precision low-noise OAmp10 amplifier with a gain of about 2 × 106, an offset voltage of less than 50 μV, and a spectral noise floor relative to the input of about 1 nV/Hz0.5. The directions for further modernization of the developed amplifiers are formulated, especially, the reduction of the parasitic collector capacitance of transistors by design engineering, applying a reverse bias voltage, and the application of nonlinear correction circuits, which allow bringing the amplifiers’ performance in the large-signal mode closer to their performance in the low-signal mode.

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.

The circuit design method has been developed for halving the static current consumption of differential stages on field-effect transistors in transimpedance and operational amplifiers, which is recommended for use in micro-power analog microcircuits. An elementary thermal model of a high-temperature integrated circuit based on silicon-carbide (SiC), gallium-arsenide (GaAs) and silicon (Si) technologies under conditions of exposure to elevated temperatures is considered for the case when the integrated circuit die (chip) releases its self-power P 0 . The permissible values of the self-heating power P 0 have been determined for SiC, GaAs and Si technological processes that ensure the operation of the integrated circuit die at a temperature not higher than a given limit value.

Three new modifications of second-order low-frequency discrete analog filters (DAFs) based on switched capacitors have been developed and studied. A distinctive feature of the DAFs under consideration is the presence of two resistors in the general feedback circuit. This allows, at constant values of the capacitances of the frequency-setting capacitors and a fixed switching frequency of electronic switches, to control the frequency of the DAF pole by changing the resistance ratio of these resistors. The basic equations for the low-pass filter gain at zero frequency, the low-pass filter gain at the pole frequency, as well as formulas for calculating the pole frequency and pole attenuation are given. In the Micro-Cap environment, computer simulation of the proposed modifications of the DAF was performed, which shows that the considered circuit solutions perform the functions of a low-pass filter.

The problem of designing nonlinear control systems by the algebraic polynomial-matrix method using quasilinear models is considered. The quasilinear models of nonlinear plants are easily created on the basis of their nonlinear equations in the Cauchy form. To create these models only the differentiability of the plants nonlinearities is required. The solution to the design problem of the nonlinear Hurwitz control systems using the algebraic polynomial-matrix method is available if the quasilinear model of the plant is controllable. The design with application of this method consists of creating the quasilinear model of the nonlinear plant, generating several polynomials, composing and solving a system of linear algebraic equations. The theorem about the global stability of the equilibrium of the nonlinear systems, represented in the quasilinear model, is proved by the method of Lyapunov functions. The numerical examples of the design of nonlinear Hurwitz control systems are given. Note to Practitioners —This article is concerned with the creation of stable nonlinear control systems with nonlinear elements since the linear systems can’t fulfill the quality requirements demanded from modern control systems. Additionally, the known design methods of nonlinear systems, such as the input-state feedback linearization, backstepping, passivity and others, require the transformation of the original nonlinear equations of the plant into some special form. These transformations are often very difficult to find and to execute. A new algebraic polynomial-matrix design method of the nonlinear control systems using the quasilinear models of nonlinear plants is proposed in the article. This method can be applied if the nonlinearities of the plant are differentiable, and the quasilinear model of the plant is controllable. The theorem about global stability of the equilibrium is proved for the systems designed with this approach. The quasilinear models are easily created on the basis of the original equations in the Cauchy form for a given nonlinear plant. The algebraic polynomial-matrix design method is very simple: the quasilinear model is created; several polynomials are calculated with the use of this model and the linear algebraic equations system is composed. The solution of this system allows us to write down the expression which defines the control law as a nonlinear function of the plant’s state variables. This system will be globally or locally stable if the conditions of the theorem or the corollaries, proved in this article, are satisfied. The numerical examples illustrate the application of the suggested approach to the design of nonlinear Hurwitz control systems for the nonlinear plants. The main advantages of this approach: the quasilinear models are created quite easily; the nonlinear control law is found as a solution to the system of linear equations. The results can be applied to the creation of nonlinear control systems of nonlinear plants in many industries: shipbuilding, aircraft construction, automobile construction, agriculture and many others.

The new circuit design of operational amplifiers with input field-effect JFets, as well as input CMOS transistors and a special transient correction circuit is considered, providing increased values of the maximum slew rate of the output voltage (SR, up to $800-1000 \mathrm{~V} / \mu \mathrm{s}$) in large-signal mode. The proposed opamp circuits have a high input resistance due to the use of field-effect transistors and are characterized by low static current consumption. The results of computer simulation of micropower op amps in the LTspice and Orcad environments for micron technological processes are presented.

Four new modifications of discrete analog filters (DAF) of second order low frequencies (LPF) on switched capacitors, which are protected by the authors of the article as objects of intellectual property, have been developed and studied. In the considered DAF family, unlike other known circuit solutions, summation of input and output signals is provided using a differential difference operational amplifier. As a result, the low-pass filter transmission coefficient in the passband does not depend on the passive elements of the circuit and is always equal to minus one. Buffer amplifiers in two DAF circuits are necessary to reduce the influence of switching circuits on transient processes. In the Micro-Cap environment, computer simulations of four modifications of DAFs were performed, showing that the proposed DAFs have the amplitude-frequency response of a low-pass filter. Sequences of pulses are given that should control four electronic keys, made, for example, on CMOS transistors. Graphs of transient processes of the DAF are shown for an input sinusoidal signal with an amplitude of 1V and a frequency of 1591 Hz, equal to the pole frequency at a switching frequency of electronic keys of 1 MHz. The DAF transmission coefficients for the input sinusoidal signal in different frequency ranges are determined. It has been established that with the selected parameters of the elements in the considered DAFs, which are low-pass filters, the input signal at a frequency of 159.10 kHz is attenuated by more than 60 dB.

A significant disadvantage of classical operational amplifiers with a complementary “folded” cascode is that in the dynamic overload mode of the input differential stage, the maximum output current of the “folded” cascode is tightly coupled to the currents of the current-stabilizing bipoles that establish its static mode. This prevents (under the static current consumption limitations of the operational amplifier) a fast recharge of the integrating correction capacitor, which limits the maximum slew rate of the output voltage. The paper discusses new circuit solutions of CBJT operational amplifier based on complementary “folded” cascodes and input differential stage of dual-input stage subclass to increase slew rate from 215 V/µs to 8000 V/µs level. The problem solved here is to provide higher levels of “folded” cascode output current during the transient edge. This effect is achieved by introducing three additional small capacitance correction capacitors into the circuit. It is possible to introduce a special current limiting resistor in series with the third additional capacitor to reduce overshoot during the transient edge. The proposed modifications of operational amplifier have significant advantages in comparison with the classical ones based on complementary “folded” cascodes in terms of slew rate level. Results of computer modeling of the operational amplifier in LTSpice environment for silicon CBJT technological process with micron topological norms are presented.

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.

The basic functional units of high-temperature operational amplifiers (OAs) based on wide-gap semiconductors (GaAs, SiC, GaN, etc.) are considered. Their basic functional units include resistance-free GaAs JFet two-terminal reference current elements that set the static mode of the input differential stage (DS) in the range of 0.08-2mA, and JFet dynamic loads with an internal resistance of 0.03-1.2M$\Omega$ both in the drain circuit and in the source circuits that determine the voltage gain of the DS. In the LTspice software, we investigated an GaAs OA circuit that does not contain integral resistors, the functions of which are performed by dynamic loads on the JFet with different channel widths. It is shown that the proposed OA circuit solutions are characterized by a low magnitude of the systematic part of the zero offset voltage.