Design of Miniaturised Wireless Systems
People    
  John Barrett   Principal Investigator
  Rafa Martinez   Design of a Multisensor RF Microtransceiver
  Pawel Rulikowski   Ultra Wideband Communication in Sensor Network

System-in-a-Package Implementation of an Intelligent RF Transceiver

How to Miniaturise?

  Complete redesign in Si
Not cost effective at low scale production
Not always feasible
Avoiding the Si design
Get rid of the package
Use smallest possible components
Use a high density multilayer PCB
Solution: MCM Technology

Multichip Module Technology (MCM) or SoP
  • System with two or more bare IC or CSP (chip size package) mounted and interconnected on a substrate.
  • The bare chips are mounted with different technologies: wire bonding, flip chip or TAB bonding and are directly attached to the substrate.
  • As a consequence of shorter interconnection distances MCMs result in much denser circuits with higher performance than conventional PCBs.
  • Three types of MCMs:
MCM-L
MCM-C
MCM-D

Multichip Module Technology (MCM) or System on a Package (SoP)
Organic substrates-based MCM-L
Based on laminated PCB tecnologies that have evolved to accomplish the denser integration requirements of today’s demands.
Comparision with MCM-C and MCM-D
Low cost.
Parallel fabrication process
Ease of repairing of reworking individual layers
Well established infrastructure
Assemblies with components in both sides
Significant CTE mismatch between substrate and die materials
Low performance and wiring desity
Poor thermal conductivity of substrate
Moisture sensitivity of materials
High Crosstalk noise

 

Ceramic substrate-based MCM-C
Substrates based on co-fired ceramic or glass-ceramic thecnologies.

Comparision with MCM-L and MCM-D
High wiring density
Better electrical and thermal conductivity than MCM-L
Assemblies with components on both sides
Flexible packaging
Superior strengh and rigidity
Parallel manufacture process
Lower wiring density than MCM-D
High dielectric constant (not suitable for high frequencies)
CTE mismatch between substrates and die materials

Silicon substrate-based MCM-D
MCM-D are formed by Deposited dielectrics and conductors on a base substrate typically made with silicon.
Comparision with MCM-L and MCM-C
Highest performance
Highest wiring density
Low dielectric constant
Good electrical proprierties
Highest costs

Advantages of MCM Technologies

Size and Weight
No packages Shorter interconnection distances Silicon IC closer to each other considerable reduction in size and weigth
Data Speed and Signal Integrity
No packages Shorter interconnection distances Better electrical proprierties Impedance of the system easier to control
Reliability/Harsh Environments
Smaller systems are easier to protect against electromagnetic interferences, liquid, gases, etc…
Low Power Consumption
Smaller system less power.
Shorter interconnections smaller losses
Technology Integration
Analog and digital functions can be mixed without serious limitations
Passive components can be integrated inside the substrate, resistors, capacitors and inductors. filters…
Different ICs technologies can be integrated in the same package. (AsGa, Si…)
Cost
Smaller systems smaller costs.
Integration of components smaller costs
IC Packages = 80% of the cost of a single IC removing the package decreasing costs.

Drawbacks of MCM technology

Electrical drawbacks
Shorter iterconnection distances voltage coupling and induced current between traces Electromagnetic analysis required to control the impedance of the system
Layout routing in multilayer systems has to be optimised to avoid an excess number of viaholes and interconnections between layers.
Thermal drawbacks
Power dissipation heat
No package Single package has to be able to remove heat generated by all the ICs.

Transceiver Design Objectives

Microcontroller (Microchip, PIC16F877), RF Transceiver (Nordic VLSI, nRF401) and memory (Microchip, 24LC32A) Configuration that offers many application fields called “Intelligent transceiver”
ICs selected regarding Si availability, functionality, size and low power consumption
Smallest possible ISM band data transceiver
Industrial Scientific and Medical band, license free
Transceiver requires only a few external components helping miniaturisation and costs
Low power consumption
The three chips can work at 3V consuming typically less than 40mA
The microcontroller and RF transceiver feature sleep mode reducing the amount of current considerably. The memory chip does not waste current if is not being used.
Sensor data collection
The microcontroller has an internal A/D converter to collect data from sensors
Low Cost
The best MCM option regarding cost MCM-L
MCM-L provides enough performance and better cost/performance rate

Intelligent Transceiver

Specifications:
MultipleI/O interface options with local A/D, data-storage
4 external input/output ports for general purpose use
A/D port provide by the microcontroller
Local data-storage 256kb provided by the EEPROM
Configurable to application requirements, host/master/slave
Embedded software RF protocols
Suitable for network environments
Transparent drop-in intelligent RF solution
No knowledge of RF required for the use
2 operating frequencies (433.92, 434.33MHz)
Two channels with output power selection
FSK (frequency shift keying) modulation
Up to 20kbit/s data rate
19x19mm outline in a standard 52 pin PLCC or BGA package format

Circuit Block Diagram


Transceiver Board


The Finished Product

  • Top side, 52 pin PLCC package, components layout
  • Bottom side, 52 pin BGA package, no components assembled
  • Top side with components assembled
    Chips mounted with wirebonding process
  • Package “Glop-topping” with liquid “encapsulant”
    Protection
    Heat dissipation

Drawbacks of MCM technology

Applications
Alarm and Security Systems
Automatic Meter Reading (AMR)
Home Automation
Remote Control, Surveillance, Automotive, Telemetry, Industrial Control,
Wireless Communications, Remote Data Logging.

3rd Generation

Design of a new Intelligent transceiver generation which includes:
2.4GHz ISM band up to 125 channels
Higher data rate up to1Mbps
Support frequency hopping
Programmabel output power
Shock Burst(tm) mode for ultra-low power operation
Low supply current (TX), typical 8mA peak @ -5dBm output power
Low supply current (RX), typical 15mA peak in receive mode
Integrated low cost antenna
Integrated Thin Film Battey Power Supply
Microcontroller Software RF Updatable
Address and CRC computation
Low power optimised Wireless protocols
Optimum size/cost solution

Smart Home Test Bed Ultra-miniature Transceiver

Further research, ultra-miniature transceiver:
  • What minimal functionality sets are required of a microtransceiver to be useful in different types of adaptive wireless environments.
  • What combinations of wireless protocols and network architectures leads to the minimum set of functionality requirements for a microtransceiver and to a transceiver which can be minimum size.
  • What circuit design solutions can be used to implement such a microtransceiver with minimum power budget and size.
  • How power is to be supplied to a microtransceiver. The use of thin film batteries with wireless recharging capabilities will be particularly studied.
  • How components which are difficult to integrate on conventional silicon ICs, such as capacitors, inductors and antennae can be incorporated in minimum size format in the microtransceiver.
  • Which combination of circuit design, power supply and transceiver manufacturing techniques lead to an optimum size/cost solution