The document discusses duplexing and its impact on receiver sensitivity in cellular phones. It describes how frequency division duplexing uses separate sub-bands for simultaneous transmission and reception. Duplex filters are needed to separate the transmit and receive frequencies and prevent transmitter noise and power from desensitizing the receiver. Issues like poor duplexer isolation, non-50 ohm impedances, and improper layout can all allow transmit signal leakage and interference with the receiver sensitivity.
Sensitivity or selectivity - How does eLNA impact the receriver performancecriterion123
it describes
1. Why need external LNA ?
2. Why does poor linearity lead to poor sensitivity ?
3. For the eLNA gain, the more the better ?
4. Why can SAW filter improve linearity ?
Sensitivity or selectivity - How does eLNA impact the receriver performancecriterion123
it describes
1. Why need external LNA ?
2. Why does poor linearity lead to poor sensitivity ?
3. For the eLNA gain, the more the better ?
4. Why can SAW filter improve linearity ?
desence,sensitivity calculation with and without external LNA, Noise figure calculation with and without external LNA and IIP3 calculation with and without external LNA
Why to do single-tone desense test ?
What is cross modulation ?
what's the difference between cross modulation and intermodulation ?
what is triple beat ?
System(board level) noise figure analysis and optimizationcriterion123
For sensitivity, what a system (board level) RF engineer can improve is only noise figure. This document describes that the noise figure concept you should know, and how to optimize it to improve sensitivity.
System(board level) noise figure analysis and optimizationcriterion123
For sensitivity, what a system (board level) RF engineer can improve is only noise figure. This document describes that the noise figure concept you should know, and how to optimize it to improve sensitivity.
desence,sensitivity calculation with and without external LNA, Noise figure calculation with and without external LNA and IIP3 calculation with and without external LNA
Why to do single-tone desense test ?
What is cross modulation ?
what's the difference between cross modulation and intermodulation ?
what is triple beat ?
System(board level) noise figure analysis and optimizationcriterion123
For sensitivity, what a system (board level) RF engineer can improve is only noise figure. This document describes that the noise figure concept you should know, and how to optimize it to improve sensitivity.
System(board level) noise figure analysis and optimizationcriterion123
For sensitivity, what a system (board level) RF engineer can improve is only noise figure. This document describes that the noise figure concept you should know, and how to optimize it to improve sensitivity.
INPUT REFERRED NOISE REDUCTION TECHNIQUE FOR TRANSCONDUCTANCE AMPLIFIERSecij
In this paper, a useful procedure to design folded cascode (FC) and recycling folded cascode (RFC) OTAs is presented. The proposed procedure is based on a simplified equation of input voltage noise in strong and weak inversion regions. The presented method considerably decreases the input referred noise of amplifiers in weak, moderate and strong inversion. The proposed amplifiers were simulated in 0.18µm CMOS
technology, achieving 36% and 25% reduction of input voltage noise @ 1Hz in strong and weak inversion, respectively, compared to the conventional FC, without increasing power consumption and silicon area.
Design and Simulation of Low Noise Amplifiers at 180nm and 90nm TechnologiesIJERA Editor
With continued process scaling, CMOS has become a viable technology for the design of high-performance low noise amplifiers (LNAs) in the radio frequency (RF) regime. This thesis presents design and simulation of LNA at 180nm and 90nm technology. The LNA function is used to amplify signals without adding noise. The work is done on Cadence Virtuoso platform and the performance parameters like transient response and Noise figure are simulated and plotted. A supply voltage of just 5mV is used here. The noise figure at 180nm is found to be 259.722mdB at 1.04502GHz and The noise figure at 90nm is found to be 183.21mdB at 1.157GHz. 1.04502GHz and 1.157GHz are the peak frequency obtained from the frequency response of the Low noise amplifier. It is observed that the noise figure varies in each technology.
LOW POWER, LOW NOISE AMPLIFIERS DESIGN AND ANALYSIS FOR RF RECEIVER FRONT END...VLSICS Design
This work is mainly to ensure the reliability of low power low noise amplifier design and analysis which is
useful for 4G receiver front ends in particularly WIMAX applications. The low noise amplifiers
implemented by using different topologies namely (a) Cascoded Common source amplifier technique(b)
Folded Cascode amplifier technique (c) Shunt feedback amplifier technique (d) Current reuse Common
gate amplifier with gm boosted technique with 90 nm TSMC CMOS technology, which is used for WIMAX
applications with 1V supply. In order to simulate and measurement the parameters such as Scattering
parameters(S21, S12 S11. S22 ),noise-figure, input matching, output matching ,stability, linearity the
Cadence ,Agilent technologies ADS and lab view graphical software have been used and Compare the
performance of the various parameters .
Design of a Low Noise Amplifier using 0.18μm CMOS technologytheijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This slide describe the techniques of digital modulation and Bandwidth Efficiency:
The first null bandwidth of M-ary PSK signals decrease as M increases while Rb is held constant.
Therefore, as the value of M increases, the bandwidth efficiency also increases.
A low dropout (LDO) voltage regulator with high power supply rejection ratio (PSRR) and low
temperature coefficient (TC) is presented in this paper. Large 1μF off-chip load capacitor is used to
achieve the high PSRR. However, this decreases the gain and pushes the LDO’s output pole to lower
frequency causing the circuit to become unstable. The proposed LDO uses rail-to-rail folded cascode
amplifier to compensate the gain and stability problems. 2nd order curvature characteristic is used in
bandgap voltage reference circuit that is applied at the input of the amplifier to minimize the TC.
The characteristic is achieved by implementing MOSFET transistors operate in weak and strong
inversions. The LDO is designed using 0.18 μm CMOS technology and achieves a constant 1.8 V output
voltage for input voltages from 3.2 V to 5 V and load current up to a 128mA at temperature between -40 °C
to 125 °C. The proposed LDO is targeted for RF application which has stringent requirement on noise
rejection over a broad range of frequency.
Development of a receiver circuit for medium frequency shift keying signals.inventionjournals
Frequency shift keying (fsk) mode of digital signal information transfer switches between two predetermined frequencies of the carrier wave, either by modulating one sine wave oscillator or by switching between two oscillators.The need for a receiver to decode an fsk signal along the transmitting medium from a digital source code within about 5 kilometer radius for security monitoring of environment informed this work. The design of a receiver circuit at a frequency of 500 kHzfor an input frequency shift keying (fsk) signal from a transmitter is presented. The receiver is to receive an RF signal, amplify it, filter it to remove unwanted signals, and recover the desired base band information. It consists of an amplifier, tuned circuitsand mixers which filters the base-band information. A comparator circuit is incorporated, to detect the digital signal received. The output from the comparators is the digital equivalent of the coded signals sent by the transmitter circuit, and transferred to a microcontroller circuit, to act as a coded signal representing information from the transmitting end. The bode-plot response of the receiver to the incoming signals using a FET tuned circuit, shows that only frequencies above 470kHz, and below 495kHz are allowed to pass through the network with a resonant frequency of 483.553 kHz and a gain of 27.734dB, while others are totally attenuated. The reliability of the designed receiver circuit was evaluated for a 1 year continuous operating period and was found to be 74.7%.Area of application of this work include electronic policing of a defined environment with good success
Similar to A Study On TX Leakage In 4G LTE Handset Terminals (20)
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
4. By Criterion
Duplexing
A typical transceiver architecture of a 4G cellular phone
is as shown below[1]:
4
5. By Criterion
Duplexing
Duplexing is required for the simultaneous
transmission and reception of signals[1].
There are two types of duplexing in use today;
time division duplexing (TDD), where the base-station
and terminal transmit in turn, and frequency division
duplex (FDD) where simultaneous transmission
occurs[1].
5
6. By Criterion
Duplexing
FDD uses two closely spaced sub-bands for
simultaneous up-link transmission and down-link
reception.
The problem is that the transmitter power
amplier (PA) amplies both the desired transmitter (Tx)
signal as well as the noise over a wide frequency range.
Some of this noise falls in the receiver (Rx) band
and desensitises the receiver. Duplex filters separate
out the Tx and Rx frequencies[1].
6
7. By Criterion
Duplexing
The band pass filter in the transmitter path
(BPFTx) passes the Tx signal through to the antenna but
stops the transmitter noise.
The band pass filter in the receiver path (BPFRx) allows
the incoming Rx signal to enter the receiver but stops
the strong Tx signal from overloading (blocking) the
receiver circuits[1].
7
9. By Criterion
Duplexer
A duplexer consists of two filters, TX filter and RX filter.
Thus, when TX signal leakages to RX port through
duplexer, there will be two frequency responses[3].
PA Transceiver
TX Filter
RX Filter
Duplexer
TX Leakage
TX Filter RX Filter
9
10. By Criterion
Duplexer
By combining the frequency response of TX filter with
which of RX filter, we’re able to get the TX-RX
isolation[1,3].
As shown above, the isolation is at least -50 dB, it
indicates that the duplexer attenuates the TX signal that
leakages to RX port through the duplexer at least 50 dB.
Thus, the isolation of duplexer should be as large as
possible or else the sensitivity may degrade[1].
10
11. By Criterion
How does TX signal interfere RX signal
In addition to poor isolation of duplexer, the TX signal
may contaminate RX signal through three mechanisms
as well :
Poor shielding
Non 50Ω impedance of TX, RX, and ANT port
Poor layout
11
12. By Criterion
Non 50Ω impedance of ANT port
Because objects (e.g. hands, head etc.) in the near-field
of the antenna affect its impedance, the matching
condition at the antenna port of the duplexer are
influenced by the near-field distortion, which leads to a
variant Tx-Rx isolation[30].
12
13. By Criterion
Non 50Ω impedance of ANT port
As shown below, the isolation depends on the
impedance from ANT port to connector[4].
Therefore, make sure the impedance is 50Ω or else the
isolation may become poor.
PA
Duplexer
Impedance
Transceiver
13
14. By Criterion
Non 50Ω impedance of TX- and RX port
The frequency response depends on the impedance of
input and output port of a filter, as shown below:
50Ω 50Ω
Non 50Ω Non 50Ω
IL(dB)
That’s why the impedance from ANT port to connector
affects isolation because it affects both the frequency
response of TX filter and RX filter, thereby changing
isolation. 14
15. By Criterion
Non 50Ω impedance of TX- and RX port
PA
Duplexer Impedance
Transceiver
Impedance
So the impedance from duplexer RX port to transceiver
affects the frequency response of RX filter. Similarly,
the impedance from PA output to duplexer TX port
affects the frequency response of TX filter.
If the frequency response of TX filter or RX filter alters,
the isolation alters as well.
Therefore, make sure the TX port and RX port
impedance are both 50Ω(If Rx is single-end) or else the
isolation may become poor.
15
16. By Criterion
Poor layout
The proper layout of duplexer is as shown below[2]:
ANT
(Tx/Rx)
TX RX
isolation
Aggressor
Victim
Make the GND among TX, RX, and ANT port as solid as
possible to enhance the isolation among the three ports.
16
17. By Criterion
Poor layout
Take AVAGO ACMD-7612 for example, the manufacturer
already makes all of its GND pins become a whole solid
GND[5].
Thus, if we make the GND among TX, RX, and ANT port
solid in PCB, the isolation can improve further.
17
18. By Criterion
Poor layout
In addition to solid GND, the GND vias should be as
many as possible or else the TX signal may couple to
RX signal through GND without enough vias[2].
ANT Port
RX Port
TX Port
ANT Port
TX Port
RX Port
18
19. By Criterion
Poor layout
The current consumption of LTE PA is large with max
power, and the high temperature may alter the
duplexer’s frequency response including isolation[2,6].
PA Dup
Thus, we need numerous GND vias to spread the
thermal issue as well.
19
20. By Criterion
Poor layout
In addition to duplexer’s isolation, it is important to
make TX, RX, and ANT traces keep away from each
other or else the TX signal may couple to RX signal as
well.
Keep away from each other
TX Trace
RX Trace
Keep away from each other
ANT Trace
RX Trace
Keep away from each other
TX Trace
ANT Trace
ANT
(Tx/Rx)
TX RX
isolation
Aggressor
Victim
20
22. By Criterion
Thus, if the grounding of shielding can is poor, the TX
signal on shielding can will interfere RX signal by
means of reflection.
Poor shielding
The PA will couple TX signal to shielding can. In other
words, there will be TX signal on shielding can.
PA Dup
TX signal
RX Matching components
RX Trace
PA Dup
TX signal
RX Matching components
RX Trace
But with good grounding, the TX signal on shielding
can will flow to GND completely instead of reflection.
So it’s important make the grounding good.
22
23. By Criterion
Poor shielding
Besides, some duplexers have metal coat, which
should be GND in PCB if the layout is good and GND
vias are enough.
TX Signal
In other words, even though there is residual TX signal
on the metal coat, which will flow to GND completely.
TX Signal
23
24. By Criterion
Poor shielding
Nevertheless, if the layout isn’t good or GND vias are
not enough, the metal coat will become a radiator,
which radiates TX signal to shielding can.
As mentioned above, if the grounding of shielding can
is poor, the TX signal on shielding can will interfere RX
signal by means of reflection.
TX Signal
RX Matching components
RX Trace
TX signal
24
26. By Criterion
Impact of Tx Leakage on the Receiver
The high power Tx signal can desensitize the receiver
through several mechanisms[1]:
Gain compression
RX Band Noise
Inter Modulation
Cross Modulation
Reciprocal Mixing
DC Offset
26
27. By Criterion
Gain compression
Take Qualcomm WTR3925 for example, it has six gain
modes, which result in different gain and linearity
individually, as shown below:
27
28. By Criterion
Gain compression
When the mobile phone is at the cell boundary, the RX
signal from base station is extremely weak due to long
distance. Similarly, the TX signal from mobile phone is
very large to maintain communication quality[2,24].
Strong TX
Weak RX
28
29. By Criterion
Gain compression
Since the desired signal is extremely weak, the LNA
gain must be kept high to lower whole noise figure to
achieve acceptable sensitivity[2].
29
30. By Criterion
Gain compression
But, as shown above, the highest gain leads to worst
linearity.
Besides, as mentioned above, the TX signal is very
strong.
Thus, with LNA’s worst linearity and strong TX signal, if
the duplexer’s isolation is not large enough, the LNA
may be in compression, i.e. saturation[2].
24 dBm
PA
Transceiver
27 dBm
P1dB = -20 dBm
Post Loss = 3 dB
TX @ LNA input
= -18 dBm
Iso = 45 dB
TX@LNA Input
Isolation 30
31. By Criterion
Gain compression
As shown below, strong TX signal can drastically
compress LNA’s gain. The large the TX signal is, the
more the LNA’s gain will decrease[2].
31
32. By Criterion
Gain compression
According to the Friis formula :
before achieving minimum noise figure, the larger the
LNA’s gain is, the lower the noise figure will be[2].
Thus, a reduction in LNA’s gain results in an increment
in noise figure, thereby aggravating the sensitivity.
LNA Gain
Noise Figure
Minimum Noise Figure
TX@LNA Input
Noise Figure
32
33. By Criterion
Gain compression
As shown right :
We can derive the formula :
Power Post-Loss PA Output
27324
Conducted Power (dBm) = PAoutput(dBm) – Post-loss(dB)
Therefore, the more the post-loss is, the larger the PA
output will be.
PAoutput
Post-Loss
33
34. By Criterion
Gain compression
As shown below, we can derive the formula :
TX@LNA input (dBm) = PAoutput(dBm) – Isolation(dB)
TX @ LNA input
= -18 dBm
24 dBm
27 dBm
PA
Transceiver
Iso = 45 dB
Thus, with constant isolation, the larger the PA output
is, the larger the TX@LNA input will be.
PAoutput
TX@LNA Input
34
35. By Criterion
Gain compression
Combining the two concepts mentioned above, we can
realize that the more the post-loss is, the larger the
TX@LNA input will be. So we should keep post-loss as
small as possible to mitigate the TX@LNA input.
Moreover, as mentioned earlier, more post-loss leads to
higher PA output power, thereby increasing current
consumption and aggravating ACLR. Both the two
influences are harmful to sensitivity.
35
36. By Criterion
DC Offset
Take BGA7L1N6 for example, which is a LTE LNA
supporting Band5(869 – 894 MHz). As shown below, the
LNA amplifies the frequency ranging from 250 – 2000
MHz[29].
In other words, TX frequency(824 – 849 MHz) will be
amplified about 13 dB by this LNA as well.
36
37. By Criterion
In this case, with -23 dBm TX signal at LNA input, the
TX signal at LNA output will be -10 dBm
(-23 dBm + 13 dB = -10 dBm).
Thus, in Rx path, the mixer’s linearity requirement is
more stringent than LNA because TX signal at mixer
input is larger than which at LNA input[24].
0 Hz
RX
TX
0 Hz
RX
0 Hz
RX
TX
-23 dBm -10 dBm
G = 13 dB
DC Offset
37
38. By Criterion
DC Offset
In addition to gain compression, DC offset is the
nonlinear effect as well. Thus, the strong TX signal may
saturate mixer, thereby producing DC offset due to
mixer’s nonlinearity[2].
For direct-conversion receiver, the RX signal down-
converts to baseband signal directly. So the DC offset
due to mixer’s nonlinearity may raise the noise floor of
down-converted baseband signal, thereby aggravating
sensitivity[2].
0 Hz
RX
TX
0 Hz
RX
DC Offset
38
39. By Criterion
DC Offset
As mentioned above, when the mobile phone is at the
cell boundary, the RX signal is extremely weak and TX
signal is very large.
Strong TX
Weak RX
Strong Blocker
Besides, there is a strong blocker presence if another
base station in another cell is near mobile terminal
[2,24].
39
40. By Criterion
DC Offset
In this case, there will be blocker and Tx signal in Rx
path simultaneously. And perhaps both of them will be
amplified by LNA[24].
Thus, there will be two DC Offset products due to
mixer’s nonlinearity. So the total DC Offset is larger,
thereby aggravating sensitivity more.
0 Hz
RX
TX Blocker
0 Hz
RX
0 Hz
RX
DC Offset(Saturation)
DC Offset due to TX(Saturation)
DC Offset due to Blocker(Saturation)
Combine
TX Blocker
G = 13 dB
-23 dBm -10 dBm-40 dBm -27 dBm
40
41. By Criterion
DC Offset
Similarly, the DC offset may also appear at LNA output
due to LNA’s nonlinearity. But in the stage, the RX
signal is still in RF frequency, so we can remove DC
offset at LNA output by means of DC block.
But RX signal is already down-converted to baseband
signal at mixer output, DC block will remove both down-
converted baseband signal and DC offset. So DC offset
due to mixer’s nonlinearity is more troublesome.
0 Hz
RX
TX Blocker
0 Hz
RX
TX Blocker
0 Hz
RX
DC Offset(Saturation)
DC Offset due to TX(Saturation)
DC Offset due to Blocker(Saturation)
Combine
41
42. By Criterion
RX Band Noise
As mentioned above, the transmitter power
amplifier (PA) amplies both the desired transmitter (Tx)
signal as well as the noise over a wide frequency
range[1].
PA
Transceiver
Especially, Band12 is the worst case
because its duplex spacing(30 MHz)
and band gap(12 MHz) are
extremely narrow[8].
PA input
PA output
RX Signal
30 MHz 42
43. By Criterion
RX Band Noise
Besides, the RX band noise is not only from transceiver
, but also from PA itself[8].
For example, we choose Qualcomm WTR3925 as
transceiver, and SKY77643-11 for PA[7,9].
WTR3925
SKY77643-11
WTR3925 SKY77643-11
RX Band Noise -150 dBm/Hz -130 dBm/Hz
Gain 30 dB
43
44. By Criterion
The total RX band noise at PA put is -119.6 dBm/Hz
RX Band Noise
With PA’s gain, the RX band noise from WTR3925 is
-120 dBm/Hz(-150 dBm/Hz + 30 dB gain) at PA output[8].
The RX band noise from PA itself is -130 dBm/Hz[9].
44
45. By Criterion
RX Band Noise
Assuming the isolation is 50 dB[31], then the RX band
noise at LNA input = -119.6 dBm/Hz – 50 dB
= -169.6 dBm/Hz
Since the thermal noise floor is -174 dBm/Hz, the actual
RX noise floor is
In other words, RX band noise make sensitivity raise
about 5.75 dB[32].
WTR3925
SKY77643-11
Actual RX band noise floor = -168.25 dBm/Hz
Thermal noise = -174 dBm/Hz
5.75 dB
Iso = 50 dB
45
46. By Criterion
RX Band Noise
Thus, the larger the isolation is, the less the de-sense
will be. The isolation should be at least 50 dB[1].
As mentioned above, if we want to improve the
isolation further, we ought to avoid the following
situations :
Poor shielding
Non 50Ω impedance of TX, RX, and ANT port
Poor layout
46
47. By Criterion
RX Band Noise
Besides, LTE requires the Tx noise
leaking into the Rx band to be <-183dBm/Hz[1].
WTR3925
SKY77643-11
RX original noise floor = -169 dBm/Hz
RX band noise = -183 dBm/Hz
RX actual noise floor = -168.83 dBm/Hz
0.17 dB
Iso = 50 dB
Take previous case for example, -183 dBm/Hz Rx band
noise makes Rx noise floor raise merely 0.17 dB, which
is an acceptable level[1].
47
48. By Criterion
RX Band Noise
As mentioned above, the total RX band noise comes
from transceiver and PA.
Thus, we should make the impedance between
transceiver and PA be closer to 50Ω to improve
DA(Driver Amplifier) linearity, thereby mitigating RX
band noise from transceiver[10].
Transceiver
DA
48
49. By Criterion
RX Band Noise
Similarly, we should make the impedance between PA
and connector be closer to 50 Ω to improve PA linearity,
thereby mitigating RX band noise from PA[10].
Besides, as mentioned above, the frequency response
of TX filter is related to the impedance between PA and
connector. So making the impedance closer to 50 Ω
is optimizing the duplexer’s isolation as well.
PA
49
50. By Criterion
RX Band Noise
In terms of ACLR, mitigating RX band noise is just
optimizing ACLR. So the ACLR should meet
specification to achieve acceptable Rx band noise[22].
Besides, mitigating RX band noise from transceiver is
also optimizing ACLR at PA input, thereby improving
ACLR at PA output further[10].
50
51. By Criterion
RX Band Noise
As mentioned above, larger PA post-loss leads to larger
PA output power, thereby aggravating TX@LNA input
and ACLR. So it proves again that to lower the PA post-
loss is beneficial for TX de-sense issue[10-12].
PAoutput
Post-Loss
PAoutput
TX@LNA Input
Post-Loss
TX@LNA Input
51
52. By Criterion
Reciprocal Mixing
During down-conversion in a receiver, reciprocal mixing
of the phase noise of a local oscillator (LO) with an
unwanted TX signal may deposit additive noise on top
of the RX signal, thereby aggravating sensitivity[13,16].
RX
TX TX
RX
Phase Noise
The undesirable reciprocal mixing may be mitigated by
implementing some skills that can minimize phase
noise of a LO[13].
52
53. By Criterion
Reciprocal Mixing
As mentioned above, chances are that there will be
blocker and Tx signal in Rx path simultaneously.
Phase Noise
RX
TX Blocker
RX
TX Blocker
Consequently, the phase noise of a LO with TX signal
and blocker may deposit stronger additive noise on top
of the RX signal, thereby aggravating sensitivity
more[13,16,17].
53
54. By Criterion
Reciprocal Mixing
Firstly, as shown below, these areas marked red should
be kept out because these areas are VCO related
circuits. Otherwise, the parasitic effect may aggravate
the phase noise of VCO.
54
56. By Criterion
Reciprocal Mixing
For these VCO, PLL, LO, and synthesizer pins, if their
Vdd is too low, the phase noise will aggravate[14-15].
Phase Noise
Besides, even though the Vdd is large enough, large IR
drop leads to low Idd, thereby aggravating phase noise.
As shown above, IR drop allowed at any WTR1605(L)
pin is 20mV. If IR drop is larger than 20mV, the phase
noise will aggravate[14-15].
56
57. By Criterion
Reciprocal Mixing
In addition to low Vdd and Idd, large ripple in voltage
supply will contribute to phase noise as well[15].
Ripple
Voltage
Time
As shown below, larger value of decoupling capacitor
results in lower phase noise due to better
decoupling[15].
57
58. By Criterion
Reciprocal Mixing
Thirdly, instead of sharing a common ground flood with
all RF transceiver ground pins, the opposite grounding
method is to keep multiple subgroupings separate from
each other until they converge on the main PCB ground
plane, especially for VCO, PLL, LO, and synthesizer
GND pins[15].
58
59. By Criterion
Intermodulation
TX signal leaks into not only RX path, but also LO port
due to parasitic coupling[16].
Thus, TX signal will self-mix and create a DC offset
signal at mixer output, thereby aggravating sensitivity.
This phenomenon is called self-mixing[1,16].
Because the product of self-mixing is due to (FTX - FTX),
we are able to regard it as 2nd order
intermodulation(IMD2) as well[16,24].
0 Hz
RX
TX
0 Hz
RX
IMD2(Self-Mixing)
0 Hz
RX
TX
TX signal
59
60. By Criterion
Intermodulation
As mentioned above, chances are that there will be
blocker and Tx signal in Rx path simultaneously.
In this case, there will be two IMD2 products due to
(FBlocker - FBlocker) and (FTX - FTX) from self-mixing. So
the total DC Offset is larger, thereby aggravating
sensitivity more.
TX signal
0 Hz
RX
TX Blocker
0 Hz
RX
TX Blocker
0 Hz
RX
IMD2(Self-Mixing)
Blocker
IMD2 due to TX(Self-Mixing)
IMD2 due to Blocker(Self-Mixing)
Combine
60
61. By Criterion
Intermodulation
Besides, Tx signal and blocker will produce IMD2
(FTX - FBlocker) due to mixer’s nonlinearity.
Although the IMD2 is not at 0Hz in spectrum, the
bandwidth(BW) of the IMD2 at baseband can be up to
twice the blocker’s or the Tx signal’s BW[16].
If Tx signal and blocker are both close to Rx signal in
spectrum, the IMD2 near 0Hz will partially or fully
interfere Rx signal with its twice BW, thereby
aggravating sensitivity[16].
0 Hz
RX
TX Blocker
0 Hz
RX
TX Blocker
0 Hz
RX
IMD2
61
62. By Criterion
Intermodulation
Similarly, Tx signal and blocker will produce IMD3
(2FTX - FBlocker) due to LNA’s nonlinearity.
Although the IMD3 is not at Rx frequency in spectrum,
the BW of the IMD3 can be up to triple the blocker’s or
the Tx signal’s BW[16].
If Tx signal and blocker are both close to Rx signal in
spectrum, the IMD3 near Rx frequency will partially or
fully interfere Rx signal with its triple BW, thereby
aggravating sensitivity[16].
0 Hz
RX
TX Blocker
0 Hz
TX Blocker
0 Hz
RX
IMD3
RX
IMD3
62
63. By Criterion
Intermodulation
If the blocker’s frequency is nearly twice the Tx signal
or Rx signal, Tx signal and blocker will produce IMD2
(FTX - FBlocker) near Rx frequency due to LNA’s
nonlinearity[18].
0 Hz
RX
0 Hz
RX
TX Blocker
0 Hz
RX
TX Blocker
IMD2 IMD2
Similarly, although the IMD2 is not at Rx frequency, the
IMD2 near Rx frequency will partially or fully interfere
Rx signal with its twice BW, thereby aggravating
sensitivity.
63
64. By Criterion
Intermodulation
If the blocker’s frequency is nearly twice the Tx signal
or Rx signal, Tx signal and blocker will produce IMD2
(FTX - FBlocker) near Rx frequency due to LNA’s
nonlinearity[18].
0 Hz
RX
0 Hz
RX
TX Blocker
0 Hz
RX
TX Blocker
IMD2 IMD2
Similarly, although the IMD2 is not at Rx frequency, the
IMD2 near Rx frequency will partially or fully interfere
Rx signal with its twice BW, thereby aggravating
sensitivity.
64
65. By Criterion
Crossmodulation
Cross modulation(XMD) occurs when a number of
tones are applied to a nonlinear system such as
amplifier. And as long as one of these tones is
amplitude-modulated.
Intermodulation occurs when a number of tones are
applied to a nonlinear system such as amplifier
regardless of whether these tones are amplitude-
modulated or not [33,34].
65
67. By Criterion
Crossmodulation
,With LNA’s nonlinearity, TX signal and blocker might
produce IMD and XMD products, which interfere with
received signal indeed.
67
68. By Criterion
Crossmodulation
,The XMD formula is as shown below:
it indicates that XMD increases by 2dB as the Tx
leakage power increases by 1dB(i.e. duplexer isolation
decreases by 1dB) [33].
68
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69
70. [16] Effective IM2 estimation for two-tone and WCDMA modulated blockers in zero-IF
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70
71. [29] Single Band LTE LNA Using BGA7L1N6 Supporting Band-5 (869- 894 MHz) Using
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71