The effect of feedback on noise figure

Iversen, Simon

doi:10.1109/proc.1975.9784

Cited by 32 publications

(8 citation statements)

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“…This can be achieved using a combination of two feedback networks (shunt and series feedback) to transform the noise parameters set of a transistor. 8 Our point of view focuses the attention of the designer on the equaliser, after having obtained a full characterisation of the photodiode and of the amplifier. In the frequency range 0-4GHz a lot of gain blocks are available which can be used for this application.…”

Section: Power Matching Approachmentioning

confidence: 99%

Design approach and performance analysis of optical receivers based on input matching network

et al. 1995

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The performance of bandpass optical receivers can be improved using a lossless cqualiscr between the photodiode and the amplifier, as a consequence of the mismatch between the source and the input section of the amplifier. We propose two design approaches based on noise matching and on power matching, as well as a performance evaluation criterion to make comparisons between these different techniques. We have found the limit noise performance of the approaches at a single frequency, and a upper bound, derived from the Bode-Fano limit, in a wide-band application for power matching approach. INTRODUCTIONThe role of narrow band optical receivers is becoming more and more important owing to the presence of distribution services which use optical signals1'2 to carry IF signals as AM-SCM and FM-SCM for CATV transmission systems. This kind of application uses a bandpass transmission channel and a subcarrier multiplexing technique. The bandwidth requirement is quite moderate (0.5-2GHz) with respect to the possibility of the optical fiber, while severe constraints are set for nonlinear distortions. The design of receivers for this kind of application can be greatly optimised taking into careful consideration the impedance matching conditions at the input interface. In section 3 the techniques to be used are presented; in section 4 a performance evaluation criterion will be set; in section 5the wide band synthesis will be presented and in section 6 a case study will be shown. Concluding remarks will be given in section 7. DESIGN APPROACHESThe basic structure of this type of optical receiver is shown in Fig. 1 and it consists of a P-I-N photodiode, a lossless equaliser and a bandpass amplifier. To introduce the design approaches we have regarded the amplifier as if it were fixed and consequently we set our attention on the lossless equaliser.3'4 In the following section we will specify suitable properties for the amplifier. Fig. 1. Input matched optical receiver.There are two design approaches in the synthesis of the lossless equaliser which can be justified by evaluating the signal and noise matching conditions at the interface between photodiode and amplifier. p psoc P -I -N 50 Q J 3 ,EQ IN 50 Amplifier EQ TOUT 50 f O-8194-1800-5/95/$6.OQ SPIE Vol. 2449 / 121 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/17/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Section: Power Matching Approachmentioning

confidence: 99%

Design approach and performance analysis of optical receivers based on input matching network

et al. 1995

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“…In the current work, first, a small‐signal microwave transistor with the series inductive/parallel capacitive feedback is characterized as a linear active two‐port in terms of the signal and noise parameters of the device and the feedback . Then, the full flexible performance characterization is carried out in terms of the feedback applied transistor through solving its highly nonlinear performance equations analytically using the performance measurement circles to determine the compatible/incompatible ( Freq ≥ Fmin, Vinreq ≥ 1, Voutreq ≥ 1, GTmin ≥ GT ≥ GTmax ) quadruplets with their ( Z S , Z L ) terminations and with feedback parameters along the whole of the device's operation band at the chosen bias condition ( V DS , I DS ).…”

Section: Introductionmentioning

confidence: 99%

Full flexible performance characterization of a feedback applied transistor with LNA applications

Güneş

Yurttakal

2019

Circuit Theory & Apps

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In this paper, the full flexible performance characterization of a transistor with series inductive/parallel capacitive feedback is carried out in terms of LNA applications. For this purpose, the input VSWR V in -maximum available gain G Tmax variations are constructed for a high technology low-noise transistor that is subject to the required noise figure F req (f ) F min (f ) along the device's operation band depending on the feedback. These V in -G Tmax variations result in the application of a design chart that indicates which value of feedback can be applied within which region of the operation band with the improvable trade-off between the V in and output VSWR V out for the Freq(f) ≥ Fmin(f). Following this, the optimum trade-off between V in and V out is made for the necessary operation frequency regions using the load impedance Z L as an instrument with the predetermined source impedance Z S . Finally, the LNA applications of a series inductive/parallel capacitive feedback applied transistor with the optimum V in , V out , and G T subject to Freq(f) ≥ Fmin(f) ≥ are also presented as distributed across the entire bandwidth in the different operation bands. It can be concluded that this rigorous work will enable a designer to utilize the entire operation frequency band of transistor through using only a single series inductive/parallel capacitive feedback for the LNA designs of Freq(f) ≥ Fmin(f) with the optimum trade-offs among its performance measures. K E Y W O R D Sfeedback, gain, microwave transistor, noise figure, stability, VSWR | INTRODUCTIONA low-noise amplifier (LNA) is the most significant part of data transmission systems since its noise dominates the overall sensitivity of the system. The challenge involved in LNA design optimization lies in enabling the transistor to amplify subject to its physical limitations and the trade-off relations among the noise, gain, and mismatching at its input and output ports within the operation domain (V DS , I DS , f). Therefore, the most significant ingredient of an LNA design optimization is the feasible design target space (FDTS), which covers the full potential performance of the transistor in question within its operation (V DS , I DS , f) domain. The FDTS must be calculated through the following two stages: (a) the signal and noise parameters of the transistor are modelled throughout its operation domain (V DS , I DS , f) using either artificial intelligence tools 1-4 or novel optimization methods such as those adopted in 5-7 ; (b) in the second *Corrections added on 08 January 2020, after first online publication: Missing symbols "" and "" throughout the paper have been added.

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“…However, today's conventional LNA design flow consists of trading-off based on the designer's experience and intuition among the often contrasting goals of low noise, high gain, and input and output matches in either iterative or non-iterative approach; none of which are not based on the full capacity of the device. Furthermore, series or shunt feedback is assessed to ease the noise/gain trade-off at the LNA's input, by bringing closer, in the source reflection coefficient plane, the optimum noise (Г opt ) and the maximum gain terminations at the device's input port [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, series or shunt feedback is assessed to ease the noise/gain trade-off at the LNA's input, by bringing closer, in the source reflection coefficient plane, the optimum noise (Г opt ) and the maximum gain terminations at the device's input port [7][8][9][10][11][12].A different design approach that consists of evaluating the noise/gain trade-off at the transistor level is introduced by Haus and Adler [13], with a new term 'noise measure (M)' tying the two key performance components of the amplifier, then this methodology is subsequently investigated in [14] and [15] and is very useful for multi-stage designs to control the overall LNA's noise figure. Firstly, because the input termination Z S determines the noise F ≥ F min , thus the input termination Z S is pre-determined to lie on the tangent constant noise and available gain circles so that the maximum power delivery is ensured for the given noise.…”

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Performance characterization of a microwave transistor subject to the noise and matching requirements

Güneş

Demi̇rel

2015

Circuit Theory & Apps

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In this paper, the gain G T of a microwave transistor is expressed analytically in terms of the mismatchings (V in ≥ 1, V out ≥ 1) at the ports, noise figure F ≥ F min and the [z]-parameter and noise parameters. Firstly, because the input termination Z S determines the noise F ≥ F min , thus the input termination Z S is pre-determined to lie on the tangent constant noise and available gain circles so that the maximum power delivery is ensured for the given noise. Then, a design configuration is constructed in the input impedance Z in -plane covering the gain and the required input and output mismatch circles within the Unconditionally Stable Working Area for the predetermined input termination Z S . Finally, the compatible (F ≥ F min , G T , V in ≥ 1, V out ≥ 1) quadrates for either required or optimum (V in ≥ 1, V out ≥ 1) couples are obtained with their (Z S , Z L ) couples from the analysis of the design configuration. Furthermore, a case study is also presented for the full flexible performance characterization of a selected microwave transistor. It can be concluded that the near future microwave transistor is expected to be identified by performance data base built by its compatible (F ≥ F min , G T , V in ≥ 1, V out ≥ 1) quadrates and the (Z S , Z L ) terminations within the device operation domain to overview all the possible low-noise amplifier designs using the full device capacity. produce high technology transistor, which is, of course, a matter of the semiconductor technology. However, the second stage is to be able to utilize the full capacity of the high technology device that necessitates to analyze the potential performance of the device based on the linear circuit and noise theories and construct the trade-off relations simultaneously among the noise, gain, mismatch losses, bias condition V DS , I DS , and operation frequency f. Thus, a feasible design target space can be built subject to the potential performance of the active device to overview all possible designs using the full capacity of the device. Otherwise, the design targets will generally either fail to be satisfied or allow working the circuit under the potential performance of the device.However, today's conventional LNA design flow consists of trading-off based on the designer's experience and intuition among the often contrasting goals of low noise, high gain, and input and output matches in either iterative or non-iterative approach; none of which are not based on the full capacity of the device. Furthermore, series or shunt feedback is assessed to ease the noise/gain trade-off at the LNA's input, by bringing closer, in the source reflection coefficient plane, the optimum noise (Г opt ) and the maximum gain terminations at the device's input port [7][8][9][10][11][12].A different design approach that consists of evaluating the noise/gain trade-off at the transistor level is introduced by Haus and Adler [13], with a new term 'noise measure (M)' tying the two key performance components of the amplifier, then this methodology is subs...

show abstract

The effect of feedback on noise figure

Cited by 32 publications

References 5 publications

Design approach and performance analysis of optical receivers based on input matching network

Design approach and performance analysis of optical receivers based on input matching network

Full flexible performance characterization of a feedback applied transistor with LNA applications

Performance characterization of a microwave transistor subject to the noise and matching requirements

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