Low Noise Amplifier (LNA) of 5 – 6 GHz using Various Architecture for LTE: A Review
Nurul Husna Kahar1*, Abu Bakar Ibrahim2, Che Ghani Che Kob3, Abdul Rani Othman4
1, 3 Faculty of Technical and Vocational, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim Perak, Malaysia
2 Faculty of Art, Computing and Creative Industry, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim Perak, Malaysia
4 Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka (UteM), 76100 Durian Tunggal Melaka, Malaysia
*Corresponding Author: [email protected]
Accepted: 1 June 2020 | Published: 15 June 2020
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Abstract: Low Noise Amplifier (LNA) portrays as a crucial component in the receiving end of the communication system. The evolution of front-end LNA receiver becomes preferable to give better performance that covered a variety of wireless standard applications such as Wi- Fi, Bluetooth, WIMAX and LTE. LNA is an integral part of wireless communication system that essentially to minimize the additional noise that influence block in the receiver of communication system. Correspondingly, the Third Generation Partnership Project (3GPP) in Release 8 discovered the long term evolution (LTE) and expresses it as evolving in mobile communication that can provide users with high-rise data rates, high in capacity and accumulates more user. This paper presents a useful insight of important reviews of a previous work for 5 – 6 GHz frequency range with various architecture significant suitable in designing LNA for LTE. To summarize, this paper gives an idea of the architecture of LNA will be of great accessibility for RF wireless communication.
Keywords: Low Noise Amplifier (LNA), LTE, communication system
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1. Introduction
Over the past decade, surprisingly communication technology grows now and then, especially in wireless industry become majorly progressed imploring internet access without any limits and urging for high data rates. Wireless communication plays a remarkable role in current transformation development. By the same token, there are a variety of wireless communication devices including Long Term Evolution (LTE), Wi-Fi, wireless local area network (WLAN) and WIMAX. LTE that is a brand new technology intend to perform in the unlicensed spectrum of 5 GHz because there are 21 non-overlying channel of 40 MHz in contrast with 2.4 GHz with only 14 channel available [1]. The range of LTE is between 100 mm – 10 mm to connect with the user besides targeting wider coverage area due to high spectral efficiency. It is called as an unlicensed spectrum as an alternative without needed to ask permission to use besides low cost to meet communication prospect. According to [2]
based on International Telecommunication Union (ITU) conducted a World Telecommunication Conference (WTC) in 2003 the allocation of radio frequency (RF) spectrum in 5 – 6 GHz range for unlicensed used and predicted the demand of mobile data traffic in 2020 would be increased dramatically to four times more than in 2015. In this case,
the design of the low noise amplifier (LNA) becomes one of the concerns in Radio Frequency (RF) receiver. A good LNA needs to contribute an excellent input impedance match, high power gain and minimum noise figure (NF) within the required range.
LTE has introduced to provide faster and more secured mobile services by increasing the bandwidth and provide better coverage. Therefore, in order to address these issues, with coverage of areas ranging up to 100 kilometres radius, LTE enable delivery to a variety of customers, which includes residential home, small and medium sized enterprises (SME) and large corporations in urban, suburban and rural areas with the expectation of possible increase in population in the future. However, LTE is not introduced to replace, but as an alternative for wireless communication. The purpose of LTE is to extend higher data speed with minimum noise interference, but may be inaccessible for non-existent coverage with several parameters such as hills, tunnels and underground parking. According to [3] during downlink and uplink when data rates are best with the LTE system manage to provide user with 300 Mbps of peak data rate downlink with 75 Mbps in uplink and designed to operate in 5 – 6 GHz range called as unlicensed spectrum.
Progression of wireless communication system become one of the fastest sections in communication industry. Together with escalation data rates, broaden coverage area it is pressing encouragement occurring in a wireless communication system. Radio frequency (RF) transmission becomes a demanding challenge in modern era communication due to daily usages, especially mobiles users has experienced new grown into a new features such as online gaming, streamed video and instant financial services that grow from time to time to connect people with one and another. Likewise, large number of services are needed in order to maximize the featured offered to be more practical. Thus, the RF system device has one of the most vital parts which is receiver architecture where’s low noise amplifier portray the desired performance in the communication system.
LTE with integration of Orthogonal Frequency Division Multiple Access (OFDMA) for downlink (DL) and Single Carrier Frequency Division Multiple Access (SC-FDMA) for uplink (UL) works in the frequency range 1 – 100 GHz, which anticipated to enhance the systems in capacity with coverage, boost user experience, versatile bandwidth operation and multi-antenna support. RF receiver in LTE act in converting signals from the transmitter for the wireless communication occurs. By all mean, RF front-end receiver designed to minimize the noise level or distortions affecting performance of the LTE in the system. As claimed by ITU, by the end of 2019, 4.1 billion people or 53.6 percent of the global population is using the Internet [4]. The astonishing growth of Internet rise for high speed Internet access leads to rapid mass-market adoption. Technology manages to provide users with high data speed from megabits to several ten megabits within per seconds. As shown in Figure 1 is a global number of internet users individuallyfrom (2005 – 2019).
Figure 1: Global numbers of internet user individually in years 2005 – 2019.
2. Literature Review
I. LTE Review:
Emerging market competition, wireless communications progressively become affordable with brand new technologies developed establish reasonable costs and low power consumptions. By referring to the demands in our daily life, mobile users has experienced new grown into a new features such as online gaming, streamed video and instant financial services is a prove that communication grow from time to time to connect people with one and another [5]. Wireless communication has an impact on people’s life with enable of data, image and video to be transferred to anywhere instantaneously make radio frequency (RF) become remarkable.
Long Term Evolution (LTE) is the next level of 4G mobile wireless broadband communication system. Deliberated over the LTE ought to be defined as 3.9G and according to the first “true 4G” is LTE advanced specify in Release 10 and LTE advanced systems have lots of purpose for both end consumers and mobile phone operator. [6], stated that LTE act as solution for services such as gaming, streaming, web browsing and live video in increasing the transmission rates from Mbit/s to Gbit/s. The frequency of 5 – 6 GHz are underlying under unlicensed spectrum to boost data rates where is the user are given power limit places on the transmitter which is the small cell that applies for any application including industrial, scientific and medical [7].
Forthwith, LTE unlicensed fit in wireless communication due to expanding user in a spectrum that have more traffic and network capacity and it is open for everybody to use [8].
On the other hand, the 5 GHz band does not have to put up with over cramped user, allowing better spectrum capability employing operate in 5, 10 and 20 MHz channel bandwidth of LTE supporting by Frequency Division Duplexing (FDD) and Time Division Duplexing
(TDD). Henceforth, the LTE system can affirm that one particular channel can be shared between multiple users adequate to use spectrum for overall grid performance with the needs up to the thousand user bands that benefits for performance.
In contrast, WLAN is using 2.4 GHz ISM band that manages to over cramp with billions of users with 500 MHz of bandwidth besides using carrier sense multiple access (CSMA) to access channel with 11 – 55 Mbps with the range of between 10m – 100m of the coverage radius for connecting [9]. The number of users for WLAN (IEEE 802.11) can support about a dozen users presumed to affect the communication system of a [10]. Table 1 illustrates a brief comparison between LTE and WLAN (IEEE 802.11).
Table 1: Comparison between LTE and WLAN
Parameters LTE WLAN (IEEE 802.11)
Frequency band 5 – 6 GHz 2.4 GHz
Range 100 mm – 10 mm 10m – 100m
Data transfer rates 300 Mbps (downlink)
75 Mbps (uplink) 11 – 55 Mbps
Number of users Thousands Dozens
II. Radio Frequency (RF) Front-end Receiver
To cope with the latest challenges, there is an endless demand of a Low Noise Amplifier (LNA) that continue to keep driving the innovation in the high rate data communication system. Today’s technology requires high speed transmission efficiency with less power consumption and LNA is one of the products that can satisfy several parameters required, such as high gain, low noise figure and acceptable input and output impedance matching. RF front-end receiver act as a key component used in communications systems to amplify very weak signals that captured by an antenna playing an important position to recover data in communication system with minimal noise figure plays as important role in the architecture [11]. LNA circuit design use a variety of architectures proposed by the researcher prior to use on the wireless applications. Thus, this paper presents a brief review of research done in the area of designing of LNA for 5 – 6 GHz range of frequency with several of architecture used in designing LNA. Figure 2 illustrate typical basic building blocks of front-end receiver.
Figure 2: Front-end receiver block diagram
Minimal noise is introduced by gain amplifier to meet Signal-to-Noise Ratio (SNR) before processing of the base that affecting overall receiver in LNA. Usually the RF front-end
receiver includes an LNA, image filter, local oscillator (LO), Intermediate Frequency Amplifier (IFA) and a mixer [12]. Intermodulation distortion is proposed to check strong interference with the function of LNA by providing a sufficient gain to overcome subsequent stage of noise occur in the circuit. This is due to the possibility to accept the signal of communication system. Besides, the receiver is relying on the circuit design where noise and distortion is an influence in the minimum specification of SNR and signal-to-noise and distortion ratio (SNDR) of the signal. The pros and cons of amplifier type used in LNA design could be practical to find applications in different transmission requirements [13].
Under those circumstances, LNA is a crucial component in the RF receiver for proper designing of the circuit by matching with range frequency.
III. Low Noise Amplifier Review :
By analysing and study the previous work done by the researcher, the architecture of recent techniques would become more understandable. A brief review on 5 – 6 GHz range frequency with several architectures of the low noise amplifier (LNA) can determine the overall performance of the communication system. Overall, LNA supposed to contribute with high gain, low noise, large wideband and high input and output. Several researches on low noise amplifier of 5 – 6 GHz range frequency using various architectures for LTE has been investigated. Most of the design of the low noise amplifier uses 0.18 µm CMOS processors.
For author [14], the design of low noise amplifier consist of source inductive degeneration topology of 5.5 GHz frequency to optimize noise figure (NF) and at high frequency. The simulation is based on 0.18µm standard RF CMOS process. The uses of cascode CS with implementing post distortion and forward biasing techniques reduce the power consumption and improve the input third intercept point (IIP3) of LNA. This approach used a diode connected with MOSFET act as IMD sinker done in cadence tool. To accomplish high IIP3, two transistors which main and auxiliary had been proposed by the author. LNA obtained input third intercept point (IIP3) of 9.20 dBm while consumed 10.8 mW from a power supply of 1.8 V. The designed architecture displayed has 11.34 dB peak gain and minimum NF of 2.33 dB at 5.5 GHz.
[15], managed to design an LNA at 5.2 GHz band by using a feedback circuit, and utilize in the baseband signal frequency. The authors implement two-stage LNA based on cascade topology with TSMC CMOS 0.18µm technology. The authors designed the feedback circuit contains of storage blocks to store previous magnitude and prevent unwanted power consumption. Authors stimulated the performance obtaining DC power consumption of 5.68–
6.75 mW under the supply of 1.8 V supply voltage. In that case, the LNA with the feedback circuit proposed managed to attain high gain from 11.39 dB to 22.74 dB with lowest noise performance at a high gain mode with 3 dB claimed to perform well compared with other research listed for WLAN application.
In [16], the authors introduced a fully integrated TSMC 0.18 µm CMOS of two stage CS-CS LNA circuit topology centred at 5.4 GHz. The current reuse technique is used to adequate minimal power consumption in the LNA. The authors construct the LNA design using common source (CS) due to the reasonable cost by supplying high gain, minimum noise and high-rise stability for targeted frequency range including matching used in parallel combination of two stage LC components which act as filter applied to achieve appealing input matching. The maximum gain achieved of 5.4 GHz is 12.554 dB with minimum Noise Figure (NF) 0.423 dB over a band width of 100 MHz. This achieved an input reflection coefficient ( and output reflection coefficient ( with -23.847 dB and –17.479 dB
while accomplishing reverse isolation ( of 20.458 dB. With a 1.2 V voltage supply for a power dissipation of 1.62 mW obtained stability factor of 1.425 which this selective LNA fulfil demands in wireless and satellite communication application.
[17], designed a 2.4/ 5.2 GHz low noise amplifier with a concurrent dual-band which feasibly utilize for WLAN application by using RF TSMC 0.18µm CMOS technology of Advanced Designed System (ADS). The authors decided to implement wideband LNA and notch filters in order to implement current-reused technique to minimize power consumption and lay out flat gain over a wider bandwidth. The authors use notch filters in the first stage output to have the lowest impact at the targeted frequency and the second stage input of the wideband LNA which formed the dual-band frequency response. By using a voltage supply of 1.8 V have a power consumption of 2.25 mW. Proposed LNA takes consideration of gain, input matching impedance and noise figure (NF) of both bands. At 2.4 GHz, LNA achieved noise figure (NF) of 1.8 dB, a power gain ( of 15.9 dB and an input return loss ( of -14 dB.
Meanwhile, at 5.2 GHz it features a noise figure (NF) of 2.7 dB, a power gain ( of 14.3 dB and an input return loss ( of -12.8 dB. As a result, the proposed dual-band LNA is appropriate for low power applications in multi-band WLAN receivers.
[18], proposed a 5 GHz 0.18µm CMOS LNA engaged with cascode topology integrated with floating-body transistors and high-Q passives on an SOI substrate to record noise figure and superior linearity performance between receiver and antenna. The author used an inductive matching element which a combination of bond wires and on-chip inductor. This LNA achieves gain ( of 11.0 dB, an input return loss ( -33 dB, a noise figure (NF) of 0.95 dB, and a third order input interception point (IIP3) of 5 dBm at 5 GHz with power consumption of 12 mW. This research is capable of supporting 802.11a WLAN applications with maximum linearity. The significant of SOI body-contact on the LNA RF performance related to enhance intermodulation performance in the circuit.
The authors introduced a low noise amplifier for LTE application at 6 GHz with ATF36163 high-performance low noise Pseudomorphic High Electron Mobility Transistor (PHEMT) fabricated by Avago Technologies [19]. The circuit topology implemented by an author is resistive shunt-feedback onto an LNA yield S-parameter by using the Advance Design System (ADS). The LNA has measured results of maximum gain ( of 15.16 dB with of -15.183 dB, at -21.688 dB and at -18.143 dB. The noise figure (NF) at 0.801 dB is achieved the targeted value of 6 GHz range frequency. The microstrip matching network resolves the difficulty to acquire maximum gain with a minimum noise figure for LTE application.
[20], proposed low noise amplifier for LTE application works at 5.8 GHz by using high- performance low noise superHEMT transistor FHX76LP factory-made by Eudyna Technologies stimulate with the Advance Design System (ADS). The L-matching network has been placed at the input and output matching to provide trade-offs between stability, gain and noise figure. The results by their LNA exhibits maximum gain ( from 5.8 GHz is 17.2 dB with minimum NF of 0.914 dB. The input-output reflection coefficients ( are -17.8 dB and -19.6 dB respectively, which is greater than 10 dB. The bandwidth enhancement of the amplifier recorded is 1.2 GHz, which compliant with sensitivity and LTE standards.
3. Discussion
Table 2.1 summarizes the design and architecture of the LNA for recent highlighted techniques discussed before in 5 – 6 GHz frequency. It shows the operating frequency, overall gain, overall noise figure, bandwidth and power consumption of the LNA designs. In LNA design, the highest gain achieved is 17.2 dB by [20] and the best noise figure obtained is 0.423 dB by [16]. Most of the gains displayed in the table are way below the value of 20 dB except [15] which obtained a maximum gain of 22.74 dB due to appropriate structures of feedback technique. This allows better performance for multiple trade-offs’ parameter between targeted range frequencies considered for successful in designing LNA. Table 2.2 illustrates the overall targeted specification of LNA according to the articles have been reviewed with reference and designers can be utilized these structures for performance improvements of the frond-end receiver.
Table 2.1: Summary of low noise amplifiers review for 5 - 6 GHz frequency
Ref. Frequency
(GHz) Technology Topology NF (dB)
Gain (dB)
BW (MHz)
Power Con.
(mW)
[14] 5.5 0.18m
CMOS
Cascode CS with source inductive degeneration and post
distortion techniques
2.33 11.34 NS 10.8
[15] 5.2 0.18m
CMOS
Two-stage LNA cascade with
feedback
3 11.39 -
22.74 NS 5.68 – 6.75
[16] 5.4 0.18m
CMOS
Two-stage CS-CS with current-reuse
technique
0.423 12.544 NS 1.62
[17] 2.4/ 5.2 NS
Dual band LNA of current-reuse
technique
1.8 2.7
15.9
14.3 NS 2.25
[18] 5 0.18 SOI
CMOS
Inductive degenerated
cascode 0.95 11 NS 12
[19] 6 NS Resistive shunt-
feedback LNA 0.801 15.16 NS NS
[20] 5.8 NS
Single stage with inductive degeneration
0.914 17.2 1.2 NS
NS = Not Stated
Table 2.2: Design specification for frond-end receiver LNA
Design Parameter Design Specification for LNA
(dB) 10
(dB) 10
(dB) 20
(dB) 10
Noise Figure (dB) 3
Stability (K) 1
4. Conclusion
LTE is also known as Long Term Evolution have lots of benefits for end user and mobile operator by implementing faster data speeds is defines by the Third Generation Partnership Project (3GPP) in Release 8. This modern communication system based on radio frequency (RF) gains interest and becomes one of the demands. Meanwhile, low noise amplifier is a crucial component in the overall receiver system by supplying maximum gain with minimal noise to achieve better execution. Reviews on various architectures has been done in this paper and one of the major challenges is circuit implementation that affecting the efficiency has been highlighted. This is because, LNA must meet several parameters such as high gain, low noise, wideband and high input/output isolation to enhance receiver sensitivity without imposing hassle on cost and power consumption. Therefore, multiple trade-offs’ topology between targeted range frequencies should be considered for successful in designing LNA.
Acknowledgements
The authors would like to express special thanks for the support especially Malaysia Ministry of Education for funding this research under Grants FRGS (2019-0015-104-02).
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