Introduction to TRMs Block diagram of a TRM Performance Requirements of a TRM Early TRM Development Efforts Modern TRMs: Single-Chip T/R Module Modern TRMs: Wafer-Scale Phased Array Modern TRMs: The Lowest-Cost Single-Chip T/R Modern TRMs: Digital Beamforming Literature Survey: X-Band Literature Survey: S-Band

1. Literature Survey
on TRMs, COTS LNA & Dwell Control Processors
1
Embedded Team
NASTP Electronics Systems Design Centre (NESDC)
National Aerospace Research and Technology Park (NASTP)
29 March, 2024

2. 2
Outlines
• Literature Survey on Architectural Choices for Transmit/Receive Modules (TRMs)
• Literature Survey on Commercial Off-The-Shelf (COTS) Low Noise Amplifier (LNA)
• Literature Survey on Implementation of Dwell Control Processors

3. 3
AESA System Architecture
LNA as a
part of TRM
Dwell control
processor

4. Transmit/Receive
Modules (TRMs)
4
Hazoor Ahmad
Embedded Team
NASTP Electronics Systems Design Centre (NESDC)
National Aerospace Research and Technology Park (NASTP)
29 March, 2024

5. 5
Outlines-TRMs
• Introduction to TRMs
• Block diagram of a TRM
• Performance Requirements of a TRM
• Early TRM Development Efforts
• Modern TRMs: Single-Chip T/R Module
• Modern TRMs: Wafer-Scale Phased Array
• Modern TRMs: The Lowest-Cost Single-Chip T/R
• Modern TRMs: Digital Beamforming
• Literature Survey: X-Band
• Literature Survey: S-Band
• Follow up Plan

6. 6
Introduction to TRMs
[Rick Sturdivant & Mike Harris] Compact Ku-Band T/R Module for High-Resolution Radar Imaging of Cold Land Processes
• Transmit/receive modules are the key components in an AESA.
• T/R modules have, at a minimum, four fundamental functions:
• To provide gain and RF power output in transmit mode
• To provide gain and low noise figure in receive mode
• To switch between transmit and receive states
• To provide phase shift for beam steering in the transmit and receive states
• 1K to 10K identical T/R modules may be used in each array face depending on the application.
GPPO Connectors offer RF
performance from DC to 65 GHz.

7. 7
Block diagram of a TRM
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• The attenuator is used in receive mode to tailor the
receive antenna pattern to reduce receive sidelobes.
• A phase shifter circuit controls the electrical insertion
phase of the TR signals, thereby steering the spatially
combined RF energy.
• Driver amplifier and power amplifier perform power
amplification and set the output power level of the
module in the transmit mode.
• A duplexer serves the following purposes:
• Connection: It links the radiating element to both the TR paths.
• Isolation: It ensures isolation between the TR paths, preventing interference.
• Termination: It terminates transmitter power that reflects back into the receive path through the circulator.
• The receive protect circuit limits the input power that reaches the sensitive LNA.
• The low-noise amplifier (LNA) provides low-noise amplification of the radar return signal and is the
principal element that establishes the system noise figure.
• T/R switches are used to switch from transmit to receive mode and are required on the front end of the
module to control signals through the phase shifter and attenuator, as shown in Figure 2.1.

8. 8
Performance Requirements of a TRM (Skipping details for now)
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• From Radar system considerations including power-aperture-gain (PAG), allowable array size, weight,
prime power, and cooling, among other considerations we can flow-down the following performance
requirements:
• The number of modules required, Size and weight per module, Power consumption requirements, Peak power
for each module, Efficiency requirements, Noise figure, Phase and amplitude control requirements, and
Module interface requirements.
• As an example, if the peak radiated power is specified as 20 kW and the array has 2,000 elements, each
T/R module will need to deliver 10W, ignoring the radiator losses.

9. 9
Early TRM Development Efforts:
[Nicholas 2012] The Development of T/R Modules for Radar Applications
MERA Module:
• The first T/R module was developed on Molecular Electronics for Radar Applications (MERA) program was constructed
using thin film on alumina hybrid integrated circuits with silicon active devices.
• One side of the module contained:
• the transmitter power chain, frequency multiplier, T/R switch, balanced mixer, and IF amplifier,
• while the reverse side contained the
• digital phase shifter, digital control, and LO amplifier.
• The overall power efficiency of the system was low due to the limited microwave performance capability of the silicon
devices.
MMIC-Based Module:
• Integration of microwave circuits on the same substrate known as monolithic microwave integrated circuits (MMICs).
• A typical X-band MMIC-based T/R module from that time period is shown in Figure 2.2.
Mid-1990s MMIC-based X-band T/R module.

10. 10
Modern TRMs: Single-Chip T/R Module
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• In this case, the low-noise amplifier (LNA), phase shifter, variable gain amplifier, and high-power amplifier are
designed into in a single GaAs or SiGe integrated circuits.
• Figure 10.1(a) show an example of a single-chip T/R module realized in GaAs.
• Advantages:
• Can achieve lower noise figures for a given process device gate length
• Can generate high output power on transmit
• Disadvantages: cost
• Figure 10.1(b) shows an image of a single-chip T/R module realized in SiGe and
• Figure 10.1 (c) shows a four-channel T/R module realized in SiGe [2].
• Advantages:
• SiGe is that it can have a five to 20 times lower cost than GaAs.
• Another feature of SiGe is that it is low power.

11. 11
Modern TRMs: Wafer-Scale Phased Array
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• A team of researchers developed a 64-element wafer-scale phased array [3].
• An image of the array is shown in Figure 10.2.
• This radar uses T/R modules with phase and amplitude control at each element of the array.

12. 12
Modern TRMs: The Lowest-Cost Single-Chip T/R
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• SiCMOS having lower cost than SiGe is also been used to realize T/R modules.
• Figure 10.3(a) shows an image of an active quadrature phase shifter realized in Si-CMOS [5, 6].
• This phase shifter can form the heart of a phased array radar since it will achieve the phase shift required to steer the
radar beam.
• Four-element transmit-and-receive chips were developed in 90-nm SiCMOS and are shown in Figure 10.3(b, c).
• The phase shifters in those die are based upon 50-GHz vector modulators.

13. 13
Modern TRMs: Digital Beamforming
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
• Digital beamforming uses circuitry that is a departure from the normal T/R module [7, 8].
• In the simplest case the T/R module consists of
• front filtering, low-noise amplifier, high-power amplifier, and mixing along with analog-to-digital conversion.
• A simplified block diagram of one element in a digital beamforming array is shown in Figure 10.4.

14. 14
Literature Survey (X-Band)
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems

15. 15
Literature Survey (S-Band)
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems

16. 16
Follow up Plan
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems
● on-the-go: Study & relating characteristics of every TRM component
● Populating list of articles by adding useful/removing unuseful
● Understanding the architectures from the articles and discussing with team

17. 17
Thank You for your attention
Questions / Feedback and your expert opinion

18. Commercial Off-The-Shelf (COTS) Low
Noise Amplifier (LNA)
18
Tehreem Fatima
Embedded Team
NASTP Electronics Systems Design Centre (NESDC)
National Aerospace Research and Technology Park (NASTP)
29 March, 2024

19. 19
Outlines-COTS LNA
● Low Noise Amplifier
● LNA deployed in Radar System
● Performance Parameters of LNA
● Calculating Performance parameters
● Common LNA Topologies
● COTS LNA used in Radar System

20. 20
Low Noise Amplifier
• An electronic amplifier that amplifies a very low signal without significantly degrading its SNR
• It amplifies both the signal and the Noise and provides high-gain
• Maintains a low level of added noise, as it has low NF
LNA
Weak Received
Signal + Noise
Amplified Signal
+ Noise
Amplifier Noise
Basic Working Principle of Low Noise Amplifier

21. 21
LNA deployed in Radar System
• Functions in the RF Front End:
• Signal Amplification: The primary function of the LNA in the RF front end is to amplify weak RF signals to levels that are detectable
and usable by subsequent stages of the receiver. It significantly increases the signal strength without significantly degrading the
signal-to-noise ratio.
• Noise Management: Maintaining a low noise figure is crucial. The LNA is designed to add as little noise as possible to the incoming
signal. This ensures that the amplified signal remains discernible from background noise, preserving signal integrity.
• Impedance Matching: The LNA is often designed to match the impedance between the antenna and subsequent receiver stages.
This optimization facilitates efficient power transfer from the antenna to the amplifier, minimizing signal loss or distortion.
• Frequency Selectivity: Some LNAs incorporate frequency selectivity, allowing them to amplify signals within a specific frequency
band while rejecting others. This feature aids in filtering out unwanted noise or interfering signals.

22. 22
Performance parameters of LNA
• Low Noise coming from Device (Low NF)
• Linearity (Measurement of third-order Intercept point IP3 and 1dB compression point P1dB)
• High Gain (S21)
• Stability (K factor)
• Matched to antenna or filter (Impedance Matching)
• Low Power Consumption
[Rick Sturdivant & Mike Harris] Transmit Receive Modules for Radar and Communication Systems

23. 23
Calculating Performance parameters
Friis's formula is used to calculate the total NF of a cascade of stages, each with its own noise
factor and power gain (assuming that the impedances are matched at each stage).
The total NF is given as:

24. 24
Rollet's stability factor (K-factor):
Stability of LNA is dependant on K factor which is calculated as :
If K-factor > 1 it shows that your amplifier is unconditionally stable.
If K < 1, you may have a problem
K-factor is only defined for two-port networks
Calculating Performance parameters

25. 25
The most prominent passband intermodulation originates from the third order nonlinearity IP3. Graphically,
the IP3 is measured by feeding the device with a two-tone signal, than plotting on a log-log scale the
fundamental output power and the third order intermodulation distortion products power (IMD3 or IM3), as a
function of the input power. These curves, shown in the left figure, are linear for small input power (black lines).
Extrapolating the linear part of the curves (dashed lines), the IP3 is the point where the two lines meet. The
input power and output power at this point are called input IP3 (IIP3) and output IP3 (OIP3).
Calculating Performance parameters

26. 26
Common LNA Topologies
• Common source (CS)
• Common gate (CG)
• Cascade
• Cascode
• Differential low noise amplifiers
• Other configurations like variable gain low noise amplifier (VGLNA), electrostatic discharge (ESD) protected LNA, transformer
feedback LNA and current reuse LNAs are also reported.

27. 27
COTS LNA used in Radar System

28. 28
Thank You for your attention
Questions / Feedback and your expert opinion

29. Dwell Control
Processors
29
Ammar Ahmed Siddiqui
Embedded Team
NASTP Electronics Systems Design Centre (NESDC)
National Aerospace Research and Technology Park (NASTP)
29 March, 2024