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Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 955

GSM Transceiver Design Optimization

Francis E. Idachaba1.* and O. O. Oni2

1 Department of Electrical and Information Engineering

Covenant University

Ota, Nigeria

2 Department of Electrical and Information Engineering

Covenant University

Ota, Nigeria

*Corresponding author’s email: idachabafe [AT] yahoo.com

_________________________________________________________________________________

ABSTRACT—Transceiver design is a tradeoff between several parameters that impact on the transceiver

specifications. These parameters are also interrelated such that an increase in one parameter impacts on the possible

values of the second parameter and these determine the specifications achievable. This work presents the design of a

GSM transceiver system and presents that achieved results in comparison to the ETSI GSM specifications. The

parameters were all subjected to the same percentage variation and Matlab software was used to develop algorithms

for determining the variations and interrelationships between the parameters .One key criteria in transceiver design is

the Noise figure and the results show that the frontend comprising of the Duplexer, LNA, the Mixer has the greatest

impact on the transceiver design while the power amplifier noise figures have very minimal effect of the overall system

noise figure. It also shows the power amplifier as the unit that consumes the most power. From the results, several

power saving techniques such as sleep modes targeted at the Power amplifiers can be implemented without having any

significant effect on the transceiver speed, The results also show an inverse relationship between the overall system

gain and the dynamic range of the transceiver such that to achieve a higher dynamic range, the system gain would

have to be reduced. . This work enables an understanding of the relationships between the different parameters of the

GSM transceiver design

Keywords—GSM, transceiver, Noise figure, Gain

_________________________________________________________________________________

1. INTRODUCTION

Radio receiver design requires a compromise between the various specifications of the system. The parameters

involved are interrelated together both in direct and indirect proportions. This linkages and interdependence coupled with

the availability of different types of the same components with different specifications, makes the design of radio

receivers and transceivers a process of compromise between the different specifications.

The low noise amplifier is desired to have a very high gain so as to reduce the effect of the noise figure of the filters

and mixer stages. A high gain however affects the mixers linearity limiting its performance [1] The system gain is

desired to be high so that the transceivers can cover longer distances but the dynamic range of the receiver is reduced by

a high system gain. This entire interrelationship between the different blocks of the transceiver makes it necessary to

perform optimization on the system design to determine the parameter changes required so as to achieve system

specifications as close as possible to the target specification.

1.1 Transceivers

Transceivers can be described as a system comprising of a direct coupled receiver and transmitter systems. Figs 1(a)

and (b) is a combination of a receiver and a transmitter to produce a single down/up conversion transceiver based in the

super heterodyne topology. Figure 1(a) is a transceiver used for the uplink direction from the GSM mobile to the base

station or a satellite uplink while 1 (b) is for transmission from the satellite down to the mobile. This is known as

Downlink. Both configurations can be combined in a single transceiver block to create a bidirectional transceiver system

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 956

IRFilter IF Filter IF Amp Filter PA

VCO

LNA

Figure 1(a): Transceiver block diagram (Uplink)

IRFilterIF FilterIF Amp

Filter

PA

VCO

LNA

Figure 1(b): Transceiver block diagram (Downlink)

1.2 Noise figure

Noise is a vital factor in digital communication system as it gives rise to bit error due to the fact that the information

which is being transmitted and received may be incorrect or lost [2].In addition Signal to Noise Ratio (SNR) at the output

of receiving system is another very significant criterion. It is a function of the transmit output power, Gain of transmit

and receive antennas, receiver noise and pathloss [3].The overall noise figure of the cascaded system can be calculated

using the Friis equation and the noise figure and gain values of each block in the system.

G1, F1 G2. F2

Input Output

Gn. Fn

Figure 2: Noise Figure, F for cascaded network

In general, cascade of n devices is given by friss equation

n

n

GGG F

GG

F

G

F

..........2121

3

1

2

1n-1 1

..........

11

F F

Where

F = Noise figure of the Receiver

S I = Signal power at the input

G = Gain of the receiver

1.3 Sensitivity

Sensitivity is the ability of the receiver to reliably detect the minimum signals in a system by specifying the strength

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 957

of the minimum signal at the input. Minimum Detectable Signal (MDS) determines the sensitivity of the receiver and is

given as [4]:

)( min

SNRBTFKMDS SB

BdBSNRdBFdBmMDS 10log10)()(174)( min

Where

SNR min =Minimum signal to noise ratio

F= Noise figure

Ts =Absolute temperature of the receivers input (⁰ K)

B= Receiver Bandwidth

Ks = Boltzmann’s constant 1.38*10-23Joules/K

2. TRANSCEIVER DESIGN PROCESS

The design of the transceiver involves selection of the various application specific integrated circuits (ASICs) such

that the overall system specification achieved will be within acceptable limits of the target specifications. The target

specifications for the GSM standard are as described by the ETSI and shown in Table 1

Table 1: ETSI 05.05 specifications

Parameters

Specification(DCS in brackets)

Sensitivity

-102 dBm (-100dBm)

Maximum receive signal strength

-15dBm

Noise figure

9.98dB(11.8dB)

C/N for BER performance

9dB

IIP3

-19.5 dBm

P1dB

-29.5dBm

Dynamic range

87dB

Up link

1710-1785MHz

Downlink

1805- 1880MHz

Channel band width

200KHz

2.1 Chip Selection

The various ASIC chips for the implementation of each of the blocks of the system to meet the ETSI specification are

identified and used in the system design.

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 958

Table 2: Selected Chips for the Transceiver UPLINK (1710-1785MHz)

Block

CHIP

G (dB)

N.F (dB)

Freq Range

OIP3

LNA

HMC375LP3

17.5

0.9

1.7-2.2GHz

34

SAW Image

reject filter

SAFCC1G74KA0

T00

-4.2

4.5

1710 – 1785MHz

100

Down

conversion

Mixer

HMC380QS16G

11

9

RF=1.7 - 2.2GHz

IF= 50 - 300MHz

19 (IIP3)

IF Filter

855625

-4.2

4.2

190MHz

(B/W 200KHz)

100

Gain Block

ADL5530

16

2.5

0 – 1GHz

(B/W 1GHz)

37dBm

Up conversion

Mixer

MAX 2039

-7.1

7.3

RF = 1.7 -2.2GHz

LO = 1.5 – 2.0GHz

IF = 0 – 350MHz

33.5dBm(IIP3)

SAW Image

reject filter

SAFCC1G74KA0

T00

-4.2

4.5

1710 – 1785MHz

100

The Power

Amplifier

HMC457Q16G

27dB

6dB

1.7 – 2.2GHz

46dBm (IIP3)

DOWNLINK (1805 – 1880MHz)

From the frequency distribution of the system, the same IF frequency value is used for the uplink and downlink, the

chips that differentiate both links are the image reject filters.

2.2 The SAW IR

The chip selected for Implementing the Image reject frequency for the uplink is the SAWEP1G84CQ0F00

2.3 The Voltage Controlled Oscillator (VCO)

With the choice of 190MHz (0.19GHz) for IF, the VCO is required to have the following frequency range.

RF – LO = IF

LOmin = RFmin – IF

LOmax = RFmax – IF

Uplink

LOmin = 1.710GHz – 0.19GHz = 1.520GHz

LOmax = 1.785GHz – 0.19GHz = 1.595GHz

Downlink

LOmin = 1.805GHz – 0.19GHz = 1.615GHz

LOmax = 1.880GHz – 0.19GHz = 1.690GHz

From the chip specifications for the VCO, the required LO frequencies for an IF of 190MHz is from 1.52GHz to a

maximum of 1.69GHz. A chip that will give this frequency value at low voltage is desired. The T0M9211 is the optimum

choice.

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 959

2.4 The Duplexer

The transceiver will utilize the same antenna for both receive and transmit so a duplexer would be required to

separate both channels. The duplexer chosen for the system is the ADF1800.

The transceiver designed based on these chips achieved the following specifications.

Table 3: Design specifications achieved and target specifications

Parameters

Design values (Achieved)

Target Specification

(DCS in brackets)

Sensitivity

-107.93 dBm

-102dBm(-100dBm)

Maximum receive signal

strength

-69.93 dBm

-15dBm

Noise figure

4.07dB

9.98dB(11.8dB)

C/N for BER performance

9dB

9dB

IIP3

-59.88dBm

-19.5 dBm

P1dB

-69.88dBm

-29.5dBm

Dynamic range

38dB

87dB

Uplink

1710-1785MHz

1710-1785MHz

Downlink

1805-1880MHz

1805- 1880MHz

Channel band width

200KHz

200KHz

From the results obtained, the transceiver designed achieved a better noise figure value than the target specification

but the IIP3, P1dB and dynamic range were below the target specification values.

3. DESIGN OPTIMIZATION USING MATLAB

Optimization in transceiver design involves a means of identifying the optimum value of the various components. The

optimization is done to determine the specification of components that can be used to achieve or approach the target

specification of the GSM receiver specifications [5].

There are three basic approaches used for circuit optimization and these are simulation based approach, equation

based approach and geometric programming [6,7,8,9]. The equation based approach is utilized using the Matlab software

to generate new specification based on the variation of the parameter values of each block.

The optimization procedure is as listed below.

(1) Determine the system specifications

(2) Apply the same percentage variation to a particular specification (gain, noise factor) of each block sequentially.

(3) Determine which component and which specification had the greatest impact on the transceiver’s overall

specifications.

(4) Based on steps 2 and 3 determine the component and parameter to alter and the amount of alteration required to

achieve the desired transceiver results.

From the optimization procedure listed above a variation value of 20% was selected to show the trend of the effect of

each component parameter on the overall system specifications. Using the Matlab software, the noise factor and the gain

values of each component were varied and their results are plotted to show their effect on the system specifications.

4. RESULTS AND DISCUSSION

The following results were obtained when the noise figure of each block was varied by a 20% change in value.

Plotting the graph to determine which component noise figure had the greatest effect on the overall system noise figure

yields the following results.

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 960

Variation of Noise factor

3.9

4

4.1

4.2

4.3

4.4

4.5

4.6

4.7

0 2 4 6 8 10 12 14

Block number

Noise Figure(dB)

Series1

DR(dB)

40.35

40.4

40.45

40.5

40.55

40.6

40.65

40.7

40.75

40.8

40.85

0 2 4 6 8 10 12 14

DR(dB)

From the graph, the first three blocks are the most critical as they have the greatest effect on the system noise

figure with a percentage variation of up to 15.38% for the LNA.

The effect of the variation of the gain of each component on both the dynamic range and the noise figure

yields the following results:

Effect of v ariation of the Block Gain parammee rs on

the system NF(dB)

3.6

3.65

3.7

3.75

3.8

3.85

3.9

3.95

4

4.05

G0 G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12

Blocks

NF(dB)

NF(dB)

The graph also shows that the gains of the first three blocks of the transceiver are the most critical and an increase in

the gain value leads to a reduction in the noise figure. From the graphs, an increase in the gain of blocks 4 to 12 had no

impact on the system noise figure.

From the formula, the dynamic range is given by:

Dynamic range = (2/3)*(11P3 – MDS)

4.1 Dynamic range optimization.

From the equation of the dynamic range, it is evident that the transceiver gain is related to the system dynamic range.

Variation of the system gain from 40dB to 100dB shows the following variation of the system gain from 40dB to 100Db

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 961

40 50 60 70 80 90 100

30

35

40

45

50

55

60

65

70

75 sysGain Vs DRange

sysGain in dB

Dynamic Range in dB

Figure 3: system gain Vs Dynamic range

From graph shown above in figure 3, the desired dynamic range and the corresponding system gain can be

determined. The result from the graph shows that a reduction in the gain leads to an increase in the dynamic range while

the results in table 1 shows that the gain of components after the IF stage have little effect on the system noise figure,

P1dB and sensitivity.

Eliminating one of the Power amplifiers and rerunning the program yielded the following

Gain

NF

MDS

Sensitivity

Dynamic

range

63.66

4.03

-113.96

-107.96

57.42

The results show an increase of the dynamic range to 57.42dB with the gain reduced to 63.66dB, the system NF

remained unaffected by the change in system gain. Table 4 shows the parameters achieved after the optimization

Table 4: Parameters achieved after optimization of the Transceiver

Parameters

Optimized values achieved

Target Specification (DCS in brackets)

Sensitivity

-107.96 dBm

-102 dBm (-100dBm)

Maximum receive signal strength

-50.54 dBm

-15dBm

Noise figure

4.03dB

9.98dB(11.8dB)

C/N for BER performance

9dB

9dB

IIP3

-27.82dBm

-19.5 dBm

P1dB

-37.82dBm

-29.5dBm

Dynamic range

57.42dB

87dB

Uplink

1710-1785MHz

1710-1785MHz

Downlink

1805-1880MHz

1805- 1880MHz

Channel band width

200KHz

200KHz

5. CONCLUSION

From the results in Table 4. the values of the components (gain and noise figure) have significant effects on

the overall system parameters. Components placed after the mixers have little effect on the system parameters.

The result also shows that the dynamic range is inversely related to the system gain. The dynamic gain can thus

be increased by reducing the power amplifier gain value. This reduction in gain can be made up for by the use of

highly directional antennas.

Asian Journal of Applied Sciences (ISSN: 2321 – 0893)

Volume 04 – Issue 04, August 2016

Asian Online Journals (www.ajouronline.com) 962

6. REFERENCES

[1] Parul Sharma1, Mrs J.Manjula, “design of low power and low noise figure gilbert mixer”, International Journal of

Advanced Research in Electrical, Electronics and Instrumentation Engineering vol. 2, April 2013.

[2] Adediran Y.A, Reyaz T A “Comparative analysis of modulation Techniques in mobile communication systems”,

proceedings of conference on GSM in Nigeria, 2003.

[3] Wireless Link Budget Analysis whitepaper, Tranzeo wireless technologies inc.

[4] B. Razavi, RF Microelectronics, Prentice-Hall, 1998.

[5] Fundamentals of RF and Microwave Noise Figure Measurements Agilent Technologies.

[6] Aggarwal .V “Analog Circuit Optimization using evolutionary algorithms and convex optimization”, MSc Thesis:

Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology. May 2007.

[7] Vancorenland. P, De Ranter. C., Steyaert. M., Gielen .G. “Optimal RF design using smart evolutionary algorithms”.

sigda.org/Archives/.../Dac/Dac2000/papers/2000/dac00/pdffiles/01_2.pdf source date:2nd October 2008.

[8] Barros M, Guilherme.J, Horta. N.”Optimization and synthesis of analog circuit and system using evolutionary

algorithm techniques”, Instituto Politecnico de lomar. Portugal 2007.

[9] Qi Z, Ziegler .M, Kosonocky .S.V, Rabaey.J.M, Mircea R.S “Multi dimensional circuit and micro-architecture level

optimization”, Proceedings of the 8th International symposium on quality electronic design (ISQED„07).IEEE

computer society. 2007.