On the Estimation of Frequency Response in Amplifiers Using Miller's Theorem

Conventional application of Miller's theorem in amplifiers often leaves a student with an erroneous impression that the approximation provides an incorrect estimate for the nondominant pole. The present paper clarifies that not only can a reasonable estimate for both dominant and nondominant poles be obtained through Miller's theorem but additional insight is offered into pole splitting, not afforded by conventional analysis.     

High-frequency transistor amplifier analysis

In this paper, some modifications are suggested to the standard procedure for high-frequency analysis of transistor amplifiers using Miller's theorem. These suggestions remove a major stumbling block in the application of this theorem and extend the range of applicability of this method.     

A simple proof of Miller's theorem

A new very simple proof of Miller's theorem with a clear physical interpretation is given. It may improve students' understanding of the theorem     

Comments on `A network theorem dual to Miller's theorem' by M.K.Kazimierczuk

The above-named work (ibid., vol.31, p.265-9, Nov. 1988) introduces a network theorem which is dual to Miller's theorem, and it is applied to the analysis of the common-emitter (CE) amplifier with emitter resistor. The same material can be found in earlier textbooks, specifically in the 1972 book by J. Millman and C.C. Halkias. It is noted that section 8-11 of that book bears the heading `Miller's theorem and its dual'. Fig. 8-19 and its related discussion are identical to the paper's Fig.1 and equations (1)-(8). Fig. 8-28, applying the concept to the CE amplifier stage, is equivalent to the paper's Fig. 2. In addition, it is argued that the usefulness of the theorem in electronic circuit analysis is questionable     

The general feedback theorem: a final solution for feedback systems

Design-oriented analysis is a paradigm based on the recognition that design is the reverse of analysis, because the answer to the analysis is the start big point for design. Conventional loop or node analysis leads to a result in the form of a "high entropy expression," which is a ratio of sums of products of the circuit elements. There are many methods of D-OA, some of them little more than shortcuts or tricks. In this paper, the spotlight is on a new approach to analysis and design of feedback systems, based on the general feedback theorem (GFT) is discussed.     

Simplified analysis of feedback amplifiers

A very simple and general method for the analysis of feedback amplifiers with large-loop gain is presented in this paper. The general properties of feedback amplifiers, such as gain and input and output resistances, are obtained using an open-loop circuit where the loading effect of the feedback network is easily taken into account. Emphasis is placed on quick, intuitive, and reliable calculations, useful for both the analysis and design of feedback amplifiers.     

On the Presentation of Miller's Theorem

Miller's theorem is an important analysis tool. Its presentation in many introductory electronic circuits texts often leads to student misunderstandings with regard to its applicability. An alternative presentation that may improve students' understanding is suggested.     

Feedback Made Easy for the Undergraduate

The increased use of linear integrated circuit amplifiers, which require feedback stabilization, has resulted in increased emphasis on teaching feedback techniques to undergraduates. This paper describes the method used at the Polytechnic Institute of Brooklyn to teach juniors how to analyze and design feedback circuits. We have found that these students can, after taking the course, analyze and design complicated feedback circuits, and test feedback amplifiers to determine (and adjust) the feedback present in an amplifier. The procedure presented in this paper is different from that used by other instructors in that we teach by example. Therefore, we do not use a block diagram approach which students have difficulty in relating to real amplifiers, but instead analyze and design actual circuits. Generality is sacrificed for clarity.     

Synthesis‐oriented double‐loop feedback model

This paper presents a new feedback model that focuses on the synthesis rather than the analysis of feedback amplifiers. First, a single‐loop synthesis‐oriented feedback model is developed that enables the full synthesis of such amplifiers in a hierarchical and systematic way. This model is subsequently extended to a double‐loop synthesis model, so that also feedback amplifiers with a characteristic input or output impedance—employing two feedback loops—can be synthesized through the same systematic approach. That these new models are suitable for synthesis lies in the fact that they map directly to the circuit level, such that the intended, asymptotic behavior as well as the various individual contributors to the deviation from this intended behavior, like finite loop gain, non‐ideal input and output impedances of the forward gain block, direct feed‐through and attenuations outside the feedback loop(s), are clearly distinguished and can be assigned to the responsible sections of the network. For this purpose, the double‐loop synthesis model makes the transfers of the two feedback networks explicitly visible, so that it gives immediate insight in how to design these networks to get the required signal transfer and characteristic impedance. Copyright © 2017 John Wiley & Sons, Ltd.     

Theoretical analysis of diffused quantum-well lasers and optical amplifiers

Diffused quantum-well (QW) distributed feedback (DFB) lasers and optical amplifiers will be theoretically analyzed in this paper. For DFB lasers, a design rule will be proposed and the validity of the design rule will be discussed with respect to changes in the injected carrier density. The range of grating period, which can be used in the design, is discussed. As a consequence, the maximum tuning range of the emission wavelength can be estimated without involving the time-consuming self-consistent simulation. The features of polarization independence of optical amplifiers achieved by using diffused QWs are also discussed. Our theoretical results successfully explain why polarization independence can achieve in the long-wavelength tail of the modal gain and absorption coefficient but not at photon energies above the transition edge. This explanation applies to other tensile-strained QWs for polarization-independent applications. The understanding is crucial for optimizing polarization-independent devices. To conclude, our analysis of the diffused QW optical devices demonstrates that QW intermixing technology is a practical candidate for not only realizing monolithic photonic integrated circuit, but also enhancing optical device performance.     

New relationships between Lyapunov functions and the passivity theorem

In this paper we study new relationships between a class of Lyapunov functions and the passivity theorem. It is proved that under some (sufficient) conditions a Lyapunov-stable system can be analysed as the feedback connection of two (strictly) passive subsystems. It is also shown that very recent adaptive schemes for linear plants of any relative degree can in a certain sense be unified through a passivity point of view.     

An Alternative Approach for Analyzing Feedback Amplifiers

A general procedure for analyzing feedback amplifiers is proposed, with the aim of introducing to undergraduate students the subject of feedback amplifier analysis in a simple manner.     

A novel representation for two-pole feedback amplifiers

A novel representation of the response of two-pole feedback amplifiers is discussed which is useful both for pedagogical and design purposes. The presented approach allows the parameters of an open-loop amplifier to be appropriately related to the closed-loop requirements such as bandwidth and settling time     

A time‐delay technique to improve GBW on negative feedback amplifiers

This paper presents a new method to improve the GBW (gain‐bandwidth product) on negative feedback amplifiers. The proposed method is based on the introduction of time‐delay elements in the feedback loop, which can be exploited to retrieve significant bandwidth enhancements. This delayed feedback concept is analyzed, and considerations are presented for first‐order amplifiers, based on theoretical analysis. The concept is simulated and further demonstrated in a practical example using a series‐shunt feedback amplifier with a TL081 operational amplifier (OA) and a 36‐m‐long coaxial cable as a delay element. Measured experimental results show a maximum bandwidth improvement of almost 90%, from a theoretical maximum of 141%. Copyright © 2007 John Wiley & Sons, Ltd.     

磁悬浮系统Bode定理的应用

针对磁悬浮系统的控制问题,研究了控制系统设计中的限制因素,指出了磁悬浮系统的稳定性一般都可以用线性化方程来进行处理,因此磁悬浮系统的设计问题主要是性能问题,而系统的性能(灵敏度)则是受到Bode积分定理的约束;分析了球在悬浮状态下的漂浮运动对系统带宽的影响,利用Bode定理,给出了磁悬浮系统所能达到的灵敏度最小值,并得到了实验验证.根据所给出的积分约束可以在设计阶段就预见到系统所能达到的性能,对系统设计具有普遍意义.     

Design of current‐mode MOSFET‐C filters using OTRAs

In this paper, third‐order current‐mode MOSFET‐C filters that use operational transresistance amplifiers (OTRAs) with little parasitic capacitance effects are presented. On the basis of the proposed systematic method and design procedure, we can efficiently synthesize third‐order active filters with OTRAs along with simplified MOSFET resistor circuits, and all virtually grounded capacitors. Third‐order current‐mode Chebychev low‐pass and high‐pass filters are realized to verify the validity of the theoretical analysis. Experimental results employing commercially available current feedback amplifiers are also given. Copyright © 2008 John Wiley & Sons, Ltd.     

Generalized Miller theorem and its applications

Four general Miller equivalent circuits, one for each of the four possible connections of two two-port networks, are derived. Based on these, a generalized Miller theorem is stated. A number of illustrative examples are included to demonstrate the power of the Miller theorem as an analytical tool in the analysis and synthesis of networks. It is pointed out that many known results such as capacitance multiplication, high input impedance of the emitter follower and the Darlington pair, and synthesis of driving point and transfer functions by some network configurations can be understood through the Miller theorem.<>     

Electronic Circuit Analysis and Design by Driving-Point Impedance Techniques

By using driving point impedance (DPI) techniques a systematic approach to the analysis of electronic circuits can be developed which helps the engineer gain insight into circuit action. The answers, representing the circuit's currents, voltages, gains, and driving-point impedances, are written down by inspection of the original circuit diagram without resorting to equivalent circuits of flow graphs. The resulting answers are in a most simple form which can be easily interpreted by inexperienced persons since the relative magnitude of each factor is known. Thus, the student rapidly obtains a "feel" for electronic circuits. The method can also be used to complement a computer-aided circuit design and analysis. A tutorial treatment of the fundamental methods is presented and two examples are given. The simple example, which is complex by ordinary standards, has five input signals and three active elements; yet the output signal voltage is written out by inspection with each step explained. The second example, a two-stage transistor feedback amplifier, is used to demonstrate how the fundamental concepts are applied to complex feedback circuits. The gain, input impedance, and output impedance of the feedback amplifier are found and approximations are used to compare the answers to ordinary solutions given for such amplifiers. The answers obtained by DPI analysis methods are also compared to equivalent answers found by node analysis.     

A Two-Pass Method of Midband AC Analysis for Multistage Transistor Amplifiers

A method of ac midband analysis of multistage bijunction and field-effect transistor amplifiers with no feedback loops is presented. The method clarifies the functioning of transistors for students and makes the analysis of an amplifier with any number of stages an easy affair. Two examples are worked to demonstrate the effectiveness and simplicity of the method.     

Design methodology for common‐mode stability of OTA‐based gyrators

This paper presents a design methodology for common‐mode (CM) stability of operational transconductance amplifier (OTA)‐based gyrators. The topology of g_m ? C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA‐based gyrators is presented. Sufficient requirements for the gyrator's CM stability, which easily can be considered during the design process of common‐mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180 nm complementary metal‐oxide‐semiconductor technology, and its CM stability is examined. Copyright © 2015 John Wiley & Sons, Ltd.