RF amplifier with automatic impedance matching system

Medeiros, Yan de; Lima, Robson Nunes de; Sousa, Francinalva Cordeiro de

doi:10.1109/lascas.2011.5750305

Cited by 4 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another way to implement a switchable matching network is to load a transmission line with switchable capacitors [31]- [34], see Fig. 4 for a 4 bit switchable implementation.…”

Section: B Loaded Transmission Line Based Matching Networkmentioning

confidence: 99%

Hardware Implementation Overhead of Switchable Matching Networks

Firrao

Annema

Vliet

et al. 2017

IEEE Trans. Circuits Syst. I

View full text Add to dashboard Cite

Nowadays, more and more RF systems include switchable matching networks to decrease the impact of the environment-dependent antenna impedance on the RF front end performance. This paper reviews the theoretical lower limit on the required number of matching states to match VSWR ranges and then presents an analysis of hardware implementations to actually implement a suitable switchable matching network. A number of matching network topologies are analyzed: PI networks, loaded transmission lines, branch line coupler based circuits, single circulators and cascaded circulators. In our investigation only narrow-band applications are targeted. For the various circuit implementations the required number of matching states for each hardware implementation is compared to the theoretical minimum number of states required for the same matching in order to benchmark their hardware implementation overhead. It appears that a matching network using cascaded circulators is the closest to the theoretical optimum for networks with a relatively low number of states: this type of matching network was implemented and analyzed in more detail.

show abstract

“…Another way to implement a switchable matching network is to load a transmission line with switchable capacitors [31]- [34], see Fig. 4 for a 4 bit switchable implementation.…”

Section: B Loaded Transmission Line Based Matching Networkmentioning

confidence: 99%

Hardware Implementation Overhead of Switchable Matching Networks

Firrao

Annema

Vliet

et al. 2017

IEEE Trans. Circuits Syst. I

View full text Add to dashboard Cite

show abstract

“…However, it is variable most of the time and imposes mismatch conditions to the amplifier, degrading important parameters such as effective output power, efficiency, and phase characteristic. For example, in mobile cell phones, the input impedance of the antenna can be considerably changed by the presence of humans in its vicinity [2]. Furthermore, a mismatch increases the reflection between blocks, and hence, decreases the RF circuit performance, considerably.…”

Section: Introductionmentioning

confidence: 99%

Active inductor-based tunable impedance matching network for RF power amplifier application

et al. 2016

View full text Add to dashboard Cite

a b s t r a c tThis paper presents the use of a new structure of active inductor named cascoded flipped-active inductor (CASFAI) in a T-type high-pass tunable output matching network of a class-E RF power amplifier (RFPA) to control the output power and enhance the efficiency. The designed CASFAI behaves as an inductor in the frequency range of 0-6.9 GHz, and has reached to a maximum quality factor of 4406, inductance value of 7.56 nH, 3rd order harmonic distortion better than À 30 dB for 0 dBm input power, while consumes only 2 mW power. In order to consider the performance of the proposed active inductor-based tunable output matching network on the output power level and power added efficiency (PAE) of RFPA, the CASFAI is applied as a variable inductor to the output matching network of RFPA. The overall circuit is designed and validated in ADS in a 0.18 mm CMOS process and 1.5 V supply voltage. The results indicate that by increasing the inductance value of the matching network in constant operating frequency, the PAE peak moves from high power to low power levels without any degradation. Therefore, it is possible to maintain the power efficiency at the same maximum level for lower input drive levels.

show abstract

“…Automatic antenna tuners may be used as solution for this. In general, an automatic antenna tuner consists of impedance sensors, a control network and a tunable matching network [6]- [24]. The sensors are used to detect the impedance mismatch or impedance value; the control network controls the state or setting of the tunable matching network that performs the actual impedance tuning from its load impedance Z load into its input impedance Z in .…”

mentioning

confidence: 99%

“…This paper presents a mathematical estimation of the minimum required number of states for narrow band switchable matching networks to match a certain load impedance range to within a smaller input impedance range. This problem was implicitly addressed in [22]- [24] for specific implementations, without giving a general approach or mathematical derivation.…”

mentioning

confidence: 99%

On the Minimum Number of States for Switchable Matching Networks

Firrao

Annema

Vliet

et al. 2015

IEEE Trans. Circuits Syst. I

View full text Add to dashboard Cite

The impedance of an antenna changes heavily with changing EM environments, while RF power amplifiers (PAs) are optimized for driving a well-defined load impedance. As a solution, switchable matching networks are used in automatic antenna tuners to match the antenna impedance to (about) the desired PA load impedance. This paper presents a theoretical treaty of the minimum number of required states for switchable matching networks to achieve sufficient matching from a certain load VSWR to a sufficiently low input VSWR. First for an arbitrary passive lossless switchable matching network, the mathematical minimum required number of states as a function of the required input VSWR and of the required load VSWR is derived. Several variants are analyzed and benchmarked: single-stage one-ring configuration, single-stage two-ring configuration, two-stage one-ring configuration and threestage one-ring configuration showing that single-ring configurations are optimum. An extension towards the required number of states for lossy matching networks is also provided.

show abstract

RF amplifier with automatic impedance matching system

Cited by 4 publications

References 5 publications

Hardware Implementation Overhead of Switchable Matching Networks

Hardware Implementation Overhead of Switchable Matching Networks

Active inductor-based tunable impedance matching network for RF power amplifier application

On the Minimum Number of States for Switchable Matching Networks

Contact Info

Product

Resources

About