A power efficient gain adjustment technique is described to realize programmable gain current mirror. The dissipation power changes over the wide gain range of structure are almost negligible. This property is in fact very interesting from power management perspective, especially in analog designs. The simple structure and constant frequency bandwidth are other ever-interesting merits of proposed structure. The programming gain range of structure is from zero up to 18dB under operating frequency range from 72 kHz to 173 MHz. The maximum power dissipation of designed circuit is only 3. 1 μ W which is drawn from 0. 7 V supply voltage. Simulation results in 0. 18 μ m CMOS TSMC standard technology demonstrate the high performance of the proposed structure.

Improving the performance of relay systems using patterns such as power allocation requires access to instantaneous channel coefficients. extraction of this information is always prone to errors and this error increases the undesirable portions of the received signal in the receiver, in addition to disrupting the relay system optimization pattern. the Fixed and variable Gain relays, according to the type of operation, have different effect on the estimation error of channel coefficients. in this paper, with a detailed examination of the effect of the estimation error of channel coefficients according to the pattern of estimation, suitable power allocation is proposed to reduce the effects of undesirable segments in the Fixed and variable Gain operation. Reference papers in this matter for power allocation always use second-order statistical data but in this paper, the estimated coefficients will be used. due to the complexity of the performance of the variable gain relay in control of the interference channel effect in two-way relay, the closed form for power allocation is presented.

In the variable parameter linear method, which is used to express systems with time-varying state-space matrices, the stability and performance of the feedback system are guaranteed, and there is a significant potential for improving efficiency. The dynamics of these systems depend on a variable parameter with time, considered in this research as the angular velocity of the reaction wheel. The values ​​of this parameter are during an unknown period but can be measured by system performance. Using the tabulation gain technique, the stability of the variable parameter system is checked, and the tabulation parameter is selected for estimating practical control factors. The convex algorithm can solve the extracted sufficient conditions converted into linear matrix inequality conditions. By solving these controlling conditions, the tabulated gain is obtained to guarantee the stability and performance of the variable parameter system. Numerical simulation results show the success of the proposed method.

In this paper, a Low Noise Variable Gain Amplifier in Ka-frequency band is designed. This amplifier is digitally controlled by using switching transistors which change the gain with an accuracy of 5-bit resolution (32 steps). The output phase shift should be minimized within a Dynamic Range of 15 dB. The proposed structure includes a Low Noise Amplifier and a Variable Gain Amplifier, with common-source structure and degenerative inductor. In the proposed structure, the main gain is achieved by LNA and the switching control bits are used in two stages of the VGA. Simulation illustrates a Noise Figure of 5. 6 dB; bandwidth of 5. 34 GHz; S11, S22 less than-14 dB and Dynamic Range of 15 dB. By using a “ compensating inductor” in the source of switching transistors, the amount of phase shift was reduced, such that within the bandwidth of 1. 5 GHz it is less than 5 degrees. The post-layout simulation results, show a Dynamic Range of 18. 7 dB; a bandwidth of 2. 5 GHz; Noise Figure of 6. 4 dB and return losses less than-10 dB. In addition to it, In EM analysis, all inductors and major RF paths are evaluated by “ Sonnet” software.

In the context of rapidly expanding Internet of Things (Io T) deployments, ensuring reliable detection and decoding of low-power, wideband signals from numerous asynchronous devices is a critical challenge. This paper presents a novel blind multiuser detection technique for Variable Processing Gain Direct-Sequence CDMA (VPG-DS/CDMA) tailored to Io T networks. Building on prior fluctuation-based autocorrelation estimators, our method removes all constraints on individual spreading gains and operates effectively in multipath fading channels. By dynamically adjusting each device’s spreading length, we demonstrate both an amplified periodic fluctuation signature and a direct relationship between fluctuation peak amplitude and spreading factor, enabling robust user separation even when signals are buried below the noise floor. Theoretical analysis proves reliable detection at extremely low SNR levels, a scenario common in battery-powered Io T sensors. We validate our approach via simulations over realistic Io T channel models and employ the Minimum Description Length (MDL) criterion to accurately estimate the active user count. Our results indicate that this blind multiuser detector can substantially improve network throughput and device scalability in dense Io T environments without prior synchronization or pilot overhead.

This paper has proposed a gain-scheduled controller with stability proof and guaranteed cost for a turboshaft driving a variable pitch propeller. In order to overcome the complexity of the nonlinear model, a linear parameter varying (LPV) model is proposed for the first time which is in affine form. Proposed model is established based on a family of local linear models and is suitable for LPV gain scheduling methods. Thus a gain scheduled design procedure is proposed which considers parameter dependent Lyapunov matrices to ensure stability and a quadratic cost function for guaranteed performance of the closed loop system. Proposed procedure also has the advantage of considering an upper bound for change rate of the scheduling signal which decreases conservativeness. Controller design problem and calculating its gain matrices is formulated in a set of Linear Matrix Inequalities which easily can be solved using LMILAB toolbox. Simulation results showed the effectiveness and practicality of the proposed procedure.

This paper presents an improved linearity variable-gain amplifier (VGA) in 0. 18-μ m CMOS technology. The linearity improvement is resulted from employing a new combinational technique, which utilizes third-order-intermodulation (IM3) cancellation mechanism using second-order-intermodulation (IM2) injection, and intermodulation distortion (IMD) sinking techniques. The proposed VGA gain cell consists of a variable-gain attenuator followed by a differential cascode amplifier as a fixed-gain stage. The continuous gain control mechanism in the first stage occurs by varying the gate voltage of an nMOS transistor. Our proposed linearization technique is applied to the fixed gain cascode amplifier of the second stage. To examine the linearity of the proposed circuit, a nonlinear analysis of the cascode amplifier based on Taylor series has been performed. The simulation results show that after linearization, the third-order input intercept point (IIP3) of the whole VGA has been improved about +18 dB at the gain of 15. 4 dB. The VGA has a voltage gain varying from-7. 5 to 19. 5 dB and a bandwidth of 830 MHz to 845 MHz. Morever, the circuit dissipates 4. 65 mW to 9. 35 mW from a 1. 8 V single supply over the entire gain range.

Background and Objectives: In wireless communications, receivers play an essential role. Among receiver architectures, the direct-conversion receiver (DCR) architecture has been selected due to its high level of integration and low cost. However, it suffers from DC offset due to self-mixing, I/Q imbalance, and flicker noise.Methods: This paper presents a new LNA-mixer with variable conversion gain (VG-LM) for wireless local area network (WLAN) applications. A low noise transconductance amplifier (LNTA) is used as the transconductance stage in the Gilbert cell mixer. The wide variable conversion gain range is achieved by the change in LNTA’s transconductance and transconductance of the mixer switching transistors.Results: The proposed LNA-mixer is designed and simulated using 0.18µm CMOS technology in Cadence Spectre RF. The post-layout simulations exhibit the proposed circuit operates at 2.4 GHz with a bandwidth of 10 MHz. In addition, the conversion gain is changed from -3.9 dB to 23.9 dB with the variation of the controlled DC voltage from 0.5 to 1.8. At the high gain, the double-sideband noise figure (DSB-NF) is less than 3.7 dB, and its third-order intermodulation point (IIP3) is -9 dBm. The power consumption is 22 mW from the supply voltage of 1.8 V. The circuit occupies 743 µm×775 µm of core chip area.Conclusion: Using the proposed circuit, the RF front end receiver does not need the low noise amplifier (LNA) and variable gain amplifier (VGA).

Background: Common variable immune deficiency (CVID) is the commonest symptomatic primary immunodeficiency and represents a heterogenous collection of disorders resulting mostly in antibody deficiency and recurrent infections. The syndrome includes impaired B-cell maturation, impaired somatic hyper mutation, reduced numbers of circulating memory and isotype-switched memory B cells, and absent or reduced plasma cells. B cell maturation antigen (BCMA) is a tumor necrosis family receptor superfamily member 17 (TNFRSF17), expressed only on B cell lines, and is essential for survival of long-lived plasma cells. The aim of this study was to evaluate mutations in BCMA in patients with CVID in compare with normal individuals in Isfahan, Iran.Methods: Blood samples were collected from 10 CVID patients with substitutive immunoglobulin therapy before immunoglobulins (Ig) infusion and 10 normal controls in ethylenediaminetetraacetic acid (EDTA) tubes then DNA samples were extracted and after the polymerase chain reaction (PCR) was done, samples were sequenced.Findings: After reviewing the results of the sequence and alignment of the sequences, no mutations in the gene were seen.Conclusion: In addition to the study of mutation in BCMA gene, BCMA gene and protein expression level should be considered to understand more aspects of this disease.

This paper presents a Transimpedance Amplifier (TIA) for high sensitivity Near Infrared Spectroscopy (NIRS). The proposed TIA is based on the Regulated Cascode (RGC) structure with an extra transistor employed to implement additional feed-forward path and achieve higher gain values. The extra transistor senses a partially amplified input signal, available in the conventional circuit, and conveys an additional ac current into the load, which provides a higher gain. In addition, a bandwidth extension method is introduced using a capacitor and resistor, which can improve amplifier’s bandwidth by 40%. The proposed TIA is designed in 0.18µm CMOS technology and achieves a transimpedance gain of 101.9dB with a -3dB bandwidth of 91.2 MHz considering 2pF of photodiode capacitance at the TIA input. The input referred noise is 4.4pA/√Hz while dissipating 151µW power.