Passive Mixer Research Articles

Analysis of a passive frequency mixer with current control by using protective intervals of heterodyne signals

A generalized technique for analyzing a current-controlled passive frequency mixer circuit using guard intervals between adjacent heterodyne signal pulses is proposed. The results of calculations and simulations in the Micro-Cap environment are presented for two cases of mixer input impedance: RLC circuit, RC circuit. The dependences of the modulus of the transfer impedance of the mixer for various durations of protective intervals are considered.

Characterization of the oil water two phase flow in a novel microchannel contactor equipped with helical wire static mixer

This study investigates an oil/water two-phase system to assess the potential efficacy of a novel passive mixer in enhancing the liquid-liquid interfacial area within a micro-channel contactor. In this system, two fluids are introduced into a microchannel with a diameter of 800 μm and a length of 20 cm, which is equipped with a stainless-steel helical wire measuring 250 μm in diameter. Throughout the experiments, both fluids are supplied at equal flow rates, and the dominant forces, including attachment and detachment forces, are examined. The results reveal a critical Weber number of 3.8 × 10−³, at which the first detachment occurs. A comparison between microchannels with and without the passive micromixer demonstrates that greater slug breakup occurs in the system incorporating the helical wire micromixer. This innovative configuration results in a significant reduction in slug/droplet size compared to a microchannel without a barrier, decreasing from approximately 600 μm to 390 μm at a flow rate of 0.8 mL/min. Additionally, a flow map is presented, illustrating three distinct flow regimes: flow contains long slug, Slug-droplet flow, and droplet flow regimes, with the droplet flow regime covering the largest area. The findings indicate that the implementation of this innovative passive mixer substantially increases the interfacial area, providing significant advantages for mass transfer applications.

Chaotic mixing coupled electromagnetic heating in a tubular reactor

To address the need for enhanced biochemical reactions and overcome the shortcomings associated with passive and active mixer fabrication, reactor designs must utilize the coupled mixing concept to address the lack of insufficient heat and mass transfer through notable alterations of the physical properties. This study introduces a tubular microwave reactor based on chaotic flow dynamics, attempting to combine the concept of active and passive mixing to stimulate the development of eddy and secondary flows through electromagnetic fields and geometric disturbance enhance heat and mass transfer. Experiments and simulation analysis validate the validity of the prediction model, and reveal the fluid flow, mixing, electromagnetic and thermal characteristics and their synergistic mechanism, and shows the potential to enhance the mass and heat transfer performance at low Reynolds number, which provides a new idea for the design of chemical reactors and biological analysis.

A Review of Pressure Drop and Mixing Characteristics in Passive Mixers Involving Miscible Liquids.

The present review focuses on the recent studies carried out in passive micromixers for understanding the hydrodynamics and transport phenomena of miscible liquid-liquid (LL) systems in terms of pressure drop and mixing indices. First, the passive micromixers have been categorized based on the type of complexity in shape, size, and configuration. It is observed that the use of different aspect ratios of the microchannel width, presence of obstructions, flow and operating conditions, and fluid properties majorly affect the mixing characteristics and pressure drop in passive micromixers. A regime map for the micromixer selection based on optimization of mixing index (MI) and pressure drop has been identified based on the literature data for the Reynolds number (Re) range (1 ≤ Re ≤ 100). The map comprehensively summarizes the favorable, moderately favorable, or non-operable regimes of a micromixer. Further, regions for special applications of complex micromixer shapes and micromixers operating at low Re have been identified. Similarly, the operable limits for a micromixer based on pressure drop for Re range 0.1 < Re < 100,000 have been identified. A comparison of measured pressure drop with fundamentally derived analytical expressions show that Category 3 and 4 micromixers mostly have higher pressure drops, except for a few efficient ones. An MI regime map comprising diffusion, chaotic advection, and mixed advection-dominated zones has also been devised. An empirical correlation for pressure drop as a function of Reynolds number has been developed and a corresponding friction factor has been obtained. Predictions on heat and mass transfer based on analogies in micromixers have also been proposed.

A 22-mW 0.9-2-GHz mixer-first receiver 8-phase overlap-suppressed 1/4 duty cycle LO for harmonic rejection

This paper presents a mixer-first wideband receiver front-end designed to achieve high linearity and harmonic rejection while minimizing power consumption. The proposed RF front-end adopts LO overlap suppression technology and uses 25 % duty cycle LO for 8-phase operation. In addition, the passive mixer with implicit capacitive stacking provides passive gain to the useful signal and improves harmonic rejection. The total power consumption of this work is less than 22 mW, the majority of which is consumed by the baseband amplifier and buffer, making it superior to existing active harmonic suppression RF front-ends in terms of low power consumption. The receiver is designed in TSMC 65-nm technology with an active area of 0.44 mm2 and is suitable for various communication standards from 0.9 GHz to 2 GHz. Post-layout simulation results show that < −15 dB S11, 16.7-dBm OOB-IIP3@80 MHz, 3.7–6.7 dB DSB-NF, 46.4–49.5 dB total system voltage gain and HRR3 of 35.4–42 dB are achieved. No active components are required for harmonic recombination.

Analysis and Design of Reactive Passive Mixers for High-Order Modulation IoT Cartesian Transmitters

Analysis and Design of Reactive Passive Mixers for High-Order Modulation IoT Cartesian Transmitters

A Highly Flexible Passive/Active Discrete-Time Delta-Sigma Receiver

This paper presents a fourth-order discrete-time direct RF-to-digital Delta-Sigma receiver architecture for flexible receivers with a wide frequency range. The use of a current-driven passive mixer with RF feedback enables high-Q bandpass filtering and relaxes the linearity requirement of the RF amplifier. In addition, the reconfigurable passive/active loop filter offers a good compromise between power consumption, linearity, and dynamic range. The other important feature of the proposed architecture is the use of a sampling frequency that is a divisor of the LO frequency. This solves several problems such as the upmixing of quantization noise, the need to reconfigure the Delta-Sigma loop when changing the LO frequency, and the use of two independent clocks for the LO and the sampling frequency. The circuit was implemented using 65 nm CMOS technology. The I/Q Direct Delta-Sigma receiver has an RF bandwidth of 20 MHz and a sampling frequency of 400 MHz. Measurement results show a very high dynamic range of up to 80 dB with a peak SNDR of 46 dB for a power consumption of 46 mW at 800 MHz.

Modified Broadband Ruthroff-Type Transmission Line Transformer Balun for Isolation-Enhanced Passive Mixer Design.

Generalized broadband operation facilitates multifunction or multiband highly integrated applications, such as modern transceiver systems, where ultra-wideband bidirectional passive mixers are favored to avoid a complex up/down-conversion scheme. In this paper, a modified Ruthroff-type transmission line transformer (TLT) balun is presented to enhance the isolation of the mixer from the local oscillator (LO) to the radio frequency (RF). Compared to the conventional methods, the proposed Ruthroff-type architecture adopts a combination of shunt capacitors and parallel coupled lines to improve the return loss at the LO port, thus effectively avoiding the area consumption for the diode-to-balun impedance transformation while simultaneously providing a suitable point for IF extraction. In addition, a parallel compensation technique consisting of an inductor and resistor is applied to the RF balun to significantly improve the amplitude/phase balance performance over a wide bandwidth. Benefiting from the aforementioned operations, an isolation-enhanced 8-30 GHz passive double-balanced mixer is designed as a proof-of-principle demonstration via 0.15-micrometer GaAs p-HEMT technology. It exhibits ultra-broadband performance with 7 dB average conversion loss and 50 dB LO-to-RF isolation under 15 dBm LO power. The monolithic microwave integrated circuit area is 0.96 × 1.68 mm2 including all pads.

A Comparative Study of Passive and Active Mixer Circuits in a Flexible a-IGZO TFT Technology

A Comparative Study of Passive and Active Mixer Circuits in a Flexible a-IGZO TFT Technology

A 55 μ W 2.4 GHz wake-up receiver with offset-based peak detection achieving −90dBm sensitivity for IoT applications

The paper proposes a 2.4 GHz ultra-low power wake-up receiver (WuRX) with offset-based peak detection and mixer-first based radio frequency (RF) front-end for IoT applications. The mixer-first based front-end eliminates RF modules to reduce power consumption. Based on the transparency of the passive mixing switches, a 2-path passive mixer (2-PPM) constructs the high-Q band-pass filter (BPF) at the RF port to improve out-of-band blocker rejection. The offset-based peak detection circuit adaptively extracts the reference voltage for the subsequent comparator according to the real-time signal amplitude of envelope detection, which eliminates the misjudgment of the comparator and improves the accuracy of demodulation. For low power consumption, a ring oscillator is used to generate the local oscillator (LO) signal and the frequency calibration scheme combined with coarse tuning and fine tuning is employed to improve the frequency stability, which completes 10-bit frequency tuning with 2 MHz resolution. Designed in TSMC 28 nm CMOS technology, the mixer-first based front-end achieves a conversion gain of 42 dB and a noise figure of 11.9 dB at 2.4 GHz, an S11 less than −15dB during 2.4–2.5 GHz. The frequency calibration scheme for the ring oscillator completes the 512 MHz dynamic range with a 2 MHz frequency tuning step. The WuRX can achieve −90dBm sensitivity with 55 μ W power consumption at 0.6 V supply voltage and the chip area of 0.19 mm × 0.24 mm.

Implementation and Application of Harmonic Reset Switching in Passive Mixers

Implementation and Application of Harmonic Reset Switching in Passive Mixers

Исследование влияния конструкции антипараллельной пары диодов с барьером Шоттки на потери преобразования гармонического смесителя 3-мм диапазона

This paper presents the design and principle of operation of a passive harmonic mixer in the 3-mm range (75-110 GHz), the active element of which is an antiparallel pair of Schottky barrier diodes (SBD). A theoretical analysis of the mixer operation was carried out. A technique for measuring conversion losses using a vector network analyzer is presented. The experimental results of a study of the dependence of the conversion losses of a harmonic mixer on the design of an antiparallel pair of DBSs are presented. The variable parameters of the antiparallel pair of diodes were the distance between the anode leads, the length of the anode lead and the diameter of the Schottky barrier contact. The dynamic range of the mixer is investigated.

A wideband low power RF Receiver Front-End for Internet-of-Things applications

This paper presents a broadband RF receiver front-end circuit that offers advantages in both area and power consumption. The design features an innovative dual-path noise-canceling Low-Noise Amplifier (LNA) circuit, achieving impedance matching and balun functionality without the need for on-chip inductors. The RF receiver front-end circuit comprises a I and Q doublebalanced quadrature passive mixers and an 25% duty-cycle LO generator. The circuit’s broadband characteristics enable it to operate across a wide range of frequency bands. It is implemented using a 65 nm CMOS process. The core circuit, including both RF and baseband signal paths, consumes a mere 12 mW of power. Test results demonstrate that the RF receiver front-end circuit achieves a conversion gain of 35–40 dB, a noise figure (NF) below 4.8 dB, and a minimum third-order intercept point (IIP3) exceeding −6.8 dBm over the 0.1–3.1 GHz frequency range. The chip’s overall footprint is compact at 0.9 mm2, with the entire RF signal path powered by a 1 V supply, offering clear advantages in terms of compactness and low power consumption.

Investigating hydrothermal mass transfer in an extremely low-pressure drop passive mixer: A three-dimensional simulation study

Static mixers with low-pressure drops have been used for mixing in many biomedical and chemical applications. This study evaluates fluid flow with hydrothermal mass transfer in two types of vortex generators in a rectangular channel. The pressure drops in this new three-dimensional model were meager for Reynolds numbers of 50, 100, and 150. The extremely low-pressure drop passive mixer (ELPD) is a rectangular duct 400 mm in length and 20 × 20 mm in height and width. To improve the static mixer's thermal and mass transfer performance, five conical barriers and four longitudinal twisted tapes, sized at 3, 6, and 9 mm, were utilized, which were used as vortex generators. The vorticities and chaotic flow resulting from these vortices cause improved mixing by elongating and folding the fluid particles responsible for mixing in laminar flow. The simulation used water as the principal fluid and a red dye as a tracer. The results of this analysis are summarized in terms of a very low-pressure drop with a high mixing index for different heights and different Reynolds numbers. The study found that utilizing an ELPD with a bar height of 9 mm resulted in significantly enhanced mixing performance across the tested range of Reynolds numbers. This improvement was as high as 94%, and the associated pressure drop was the lowest among all tested configurations. Conversely, the research revealed that the 6 mm twisted tape height performed poorly in terms of both mixing improvement and heat transfer compared to the 3 mm and 9 mm heights. Considering these findings, utilizing an ELPD with a 9 mm bar height is recommended for optimal mixing performance.

A 250-GHz Wideband Direct-Conversion CMOS Receiver Adopting Baseband Equalized Low-Loss Resistive Passive Mixer

A 250-GHz Wideband Direct-Conversion CMOS Receiver Adopting Baseband Equalized Low-Loss Resistive Passive Mixer

Two-dimensional tellurium-based diodes for RF applications

The research of two-dimensional (2D) Tellurium (Te) or tellurene is thriving to address current challenges in emerging thin-film electronic and optoelectronic devices. However, the study of 2D-Te-based devices for high-frequency applications is still lacking in the literature. This work presents a comprehensive study of two types of radio frequency (RF) diodes based on 2D-Te flakes and exploits their distinct properties in two RF applications. First, a metal-insulator-semiconductor (MIS) structure is employed as a nonlinear device in a passive RF mixer, where the achieved conversion loss at 2.5 GHz and 5 GHz is as low as 24 dB and 29 dB, respectively. Then, a metal-semiconductor (MS) diode is tested as a zero-bias millimeter-wave power detector and reaches an outstanding linear-in-dB dynamic range over 40 dB, while having voltage responsivities as high as 257 V ⋅ W−1 at 1 GHz (up to 1 V detected output voltage) and 47 V ⋅ W−1 at 2.5 GHz (up to 0.26 V detected output voltage). These results show superior performance compared to other 2D material-based devices in a much more mature technological phase. Thus, the authors believe that this work demonstrates the potential of 2D-Te as a promising material for devices in emerging high-frequency electronics.

Single Antenna and No Circulator Full-Duplex With 52 dB Wideband Self-Interference Suppression

Full-duplex (FD) enables high spectrum efficiency and dynamic spectrum accessing, although its application is restricted by significant self-interference. In this work, we present an integrated, single antenna, wideband FD self-interference suppression front-end solution, targeting for short-range wireless communication. Based on the characteristic of bi-directional signal transparency of N-phase passive mixer, a mixer-first active electrical balance self-interference suppression architecture is proposed. As no costly and space-consuming out-of-chip circulator is needed, compared with traditional single antenna suppression solutions, it is attractive for cost and area saving In addition, to alleviate the multi-path effect, a two-tap baseband self-interference suppression is adopted, which also helps broaden the self-interference suppression bandwidth. The fabricated FD front-end chip, employing 180nm CMOS process, has a noise figure (NF) of 8.6dB, and at the maximum TX power, the NF is degrade by 4.9dB. Test results show the achieved self-interference suppression depth is up to 52dB over 30MHz, with a much smaller antenna interface and chip size which is 0.75 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> , compared with other dual and signal antenna solutions. The wireless communication function of the propose FD front-end has been verified and the operation carrier frequency range is 0.4-1.2GHz.

Characterization of passive microfluidic mixer with a three-dimensional zig-zag channel for cryo-EM sampling

Microfluidic mixing is an essential unit operation in miniaturized analytical systems. Achieving high mixing efficiency is considerably difficult in conventional microfluidic micromixers because the fluid flow is generally associated with a laminar flow regime and is dominated by molecular diffusion. In this study, different microfluidic passive mixer devices are designed, simulated, and tested. Passive microfluidic mixers, such as straight, 2D zig-zag, and 3D zig-zag geometries, are evaluated to assess the mixing efficiency of each layout. The mixing performance is investigated, and the comparison of experimental results with computational simulations determines the mixing efficiencies. We characterized the 3D zig-zag channel to perform a promising design for improving mixing in a microfluidic passive mixer device and can be optimized to enhance mixing efficiency by the appropriate length of the microfluidic mixer. A passive micromixer with a 3D zig-zag channel is further demonstrated by characterizing mixing at varying Reynolds numbers of 18.5 ≤ Re ≤ 55.5. Finally, we validate the utility of the mixing device for the screening of detergents for a preferential orientation issue of influenza A virus hemagglutinin protein particles in cryo-EM integrated with a microfluidic spraying approach. The results reported here are versatile, reproducible, and readily adaptable to various fields needing a fast and reliable aqueous phase mixing strategy.

Application of split and recombine microchannel for microfluidic applications: a review

Microfluidic mixing is used in micro-scale systems to combine numerous samples quickly but thoroughly. These devices promote sample mixing primarily by improving the diffusion result among the fluxes of several species. In general, there are two types of microfluidic mixing methods: active (which employs an external power force to disturb the specimen genus) and passive (which uses specifically designed microchannel to-pologies to increase the area of contact as well as contact period of the sample species). This review research uses a comprehensive survey under the microfluidic micromixer (active and passive micromixer). Along with a study of hybrid active and passive micro-mixers, the use of microfluidic is also thoroughly examined. Based on this analysis, we were able to compare the mixing indexes of active and passive mixers, with active achieving a maximum mixing index of 0.73 and passive achieving a maximum mixing index of 0.97. At the end of this review, readers will have a better knowledge of microfluid-ics and its applications in the real world.

A novel S-band high linear passive mixer with an integrated driver amplifier

A novel S-band high linear passive mixer with an integrated driver amplifier