Active Matching Network Research Articles

A Miniature Actively Matched Antenna for Power-Efficient and Bandwidth-Enhanced Operation at Low VHF

Active matching techniques with non-Foster reactive elements have been introduced to overcome fundamental performance limits on electrically small passive antennas. While several experimental studies have demonstrated successful bandwidth enhancement with active matching applied to small unmatched passive antennas, their radiation performance against similar-sized, efficient, resonant antennas alone (and/or applied to active matching) has not yet been confirmed to assess their effectiveness for practical wireless communications applications. Beginning with a highly miniaturized efficient resonant antenna (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /50 in height), we design an active matching network derived from an antenna impedance model. We conduct an extensive simulation analysis to address challenging issues associated with the design arising from a tradeoff between degree of bandwidth enhancement and stability of the matching network. Based on experimental performance assessment, the effective 3 dB bandwidth of the proposed actively matched antenna is improved by more than three times compared with the passive version and improved in efficiency by more than 10 dB relative to cases that apply active matching techniques to similar-sized, unmatched passive antennas.

Methodology for broadband matching of electrically small antenna using combined non-Foster and passive networks

Decreasing the electric length of an antenna results in increasing its input reactance that becomes greater than its input resistance, resulting in a significant rise in its quality factor and in a drastic reduction of its potential operating bandwidth. For such small antennas, namely ESA for Electrically Small Antenna, passive matching is restricted by the gain-bandwidth theory, providing narrow bandwidths and/or poor gain. This limitation can be overtaken by using antenna matching networks based on non-Foster components. In previous studies, non-Foster components are used to cancel the reactance part of the ESA, and then passive matching may be introduced to transform the net input impedance toward 50Ω, which leads to an increase in the bandwidth. In this paper, a design methodology is put forward on three different topologies all based on combined passive and active matching networks. A described step-by-step design to decrease the antenna quality factor is discussed. A comparison is made between these topologies along with a discussion on their limitations and ability to increase the bandwidth and radiation efficiency of ESA. The third topology presented in this paper is a novel one that proposes a three-stage matching network and exhibits both the widest matched bandwidth and an increase in the efficiency of the whole system compared to previous approaches. In order to make this comparison, a new indicator to estimate the whole system radiated power efficiency is introduced and validated by comparison with a full EM simulation. Moreover, actual implementation of the two most interesting techniques are detailed and associated measured results are carefully compared to simulations.

40 dB-Isolation, 1.85 dB-Insertion Loss Full CMOS SPDT Switch with Body-Floating Technique and Ultra-Small Active Matching Network Using On-Chip Solenoid Inductor for BLE Applications

In the IoT/wearable devices, the antenna is shared with the receiver and transmitter of the transceiver. This requires the control of the switch between the antenna and the control circuitry to achieve both low insertion loss and high isolation. This paper presents a low insertion loss and high isolation switch based on Single Pole Double Throw (SPDT) switch for 2.4 GHz Bluetooth low power (BLE) transceiver. The body-floating technique is used to improve the insertion loss’s performance. An ultra-small on-chip matching network with high Q-factor is proposed. The shunt transistors are used as active shunt capacitors that create the active matching network to improve isolation characteristics. The proposed SDPT switch was designed using 55 nm CMOS process with the total area of 110 μm × 210 μm. The insertion loss and isolation characteristics of the proposed SPDT switch observed at 2.4 GHz are 1.85 dB and 40 dB, respectively.

Broadband CMOS mixer cell for UWB applications

AbstractA broadband mixer cell with active matching network was developed using commercial 0.25‐μm CMOS technology. From experimental results, the down‐converter with the proposed mixer cell achieves a RF input return loss greater than 10 dB from 3.1 to 23.3 GHz. For UWB low‐band application, it achieves a conversion gain of −9.2 dB and an input P1dB greater than −3 dBm at the moderate LO power level of 4 dBm. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 127–128, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22026

Novel GaAs monolithic multistage X–Ku band amplifier

A novel design approach to a wideband GaAs microwave monolithic amplifier is presented using the principle of feedback and active matching networks. The multistage amplifier utilises a unique biasing circuit which requires only one biasing voltage. A 6-18 GHz multistage amplifier has been demonstrated using the proposed approach. The amplifier has low input/output VSWR, a maximum of 20 dB gain and at least 15 dBm of output power.