VLSI-Digital VLSI Circuit Design

Digital VLSI Circuit Design

Fundamentals

• Logic Styles (NMOS, CMOS, Bipolar, Pseudo-NMOS, Dynamic CMOS, Transmission

Gate, Pass Transistor logic etc.)
Implementation Technologies (Full-Custom design and Semi-Custom design including

• ASIC (MPGA and SBIC), FPLD (CPLD and FPGA) etc.)

• Boolean Logic

• Logic Minimization

 Practical Aspects

• Combinational Logic Design: Adders, Multipliers, Multiplexers, ALUs etc.

• Sequential Logic Design: Registers, Register Files, Counters, Shift Registers, Finite State

          Machines (FSM) etc.

• Memory Design: RAM (SRAM, DRAM), ROM (PROM. EPROM, EEPROM, Flash) etc.

• Electronic Design Automation (EDA), Computer Aided Design (CAD), Computer Aided
• Engineering (CAE) tools
• System-level, Architecture-level, Register Transfer (RT) Level design.  
• High-Level or Behavioral Synthesis/Architecture Description Language (ADL/)Systemon-
  Chip (SOC) Design/Analog and Mixed-Signal (Digital + Analog) Design .
• Computer Architecture (Architecture Level)
• VHDL (or Verilog) Modeling and Synthesis (RT-Level)
• Microprocessor (System-Level)
• Clock Generators and Clock Buffers
• Clock Synchronizers, Clock Managers, Clock Tree Insertion
• Test Synthesis, Fault Analysis, Scan-chain
• Speed (Delay)
• Power Consumption
• Cost
• Reliability
• Logic-Level (Gate-Level), Circuit-Level (Transistor-Level) and Physical Design
  (Mask/Silicon-Level) Design/Layout Synthesis
  

VLSI-Very Large Scale Integration

VLSI-Very Large Scale Integration

1.VLSI Design or VLSI Circuit Design refers to
designing high-density electronic circuits, typically
circuits that contain transistor in excess of 100,000.
2.There are 2 types of VLSI Circuits-Analogue and
Digital.
3.VLSI Circuit Design typically (and in this class)
involves discussions about different logic styles and
implementation technologies for implementing
digital circuits, transistor and mask-level layout and
interconnect, fabrication technologies and analysis of
various design and performance parameters such as
Speed, Power, Cost, Reliability etc.
4.The discussion typically is at Logic (Gate), Circuit
(Transistor) and Physical/Mask (Silicon) Level.
5.Integration simply means more devices per chip.
Integration improves design, that is its speed, power
consumptions, size—and reduces manufacturing
costs.

The Global System for Mobile (GSM)

GSM uses both TDMA and Frequency Division Multiple Access (FDMA) to transmit and recover information as shown in Figure 1. These systems use data packets at specific times at specific frequencies. Thus, several conversations take place simultaneously and at the same frequency using different time slots. Systems are also frequency duplex so that the transmitting and receiving frequencies are different, and both sides of the transmission (Mobile-to-Base and Base-to-Mobile) are concurrent.  The characteristics of GSM system are shown in Table 1. The spacing between the carriers in GSM system is 200 kHz. Eight time slots carry speech and data in a GSM system.  The bandwidth for the GSM system is 25 MHz, which provides 125 carriers each having a bandwidth of 200 kHz. Due to interference to other systems, the very first carrier is not used, thus reducing the number of carriers to 124.  With eight users per channel there are about 1,000 actual speech or data channels. The number of channels will double to about 2,000 as the half rate speech coder is introduced. The frequency band used for the uplink is 890 MHz to 915 MHz (from MS to base station) and for the downlink 935 MHz to 960 MHz (from base station to MS).

The modulation method in GSM is Gaussian Minimum Shift Keying (GMSK), which facilitates the use of narrow bandwidth and coherent detection capability. In GMSK the rectangular pulses are passed through a Gaussian filter prior to their passing through a modulator. This modulation scheme almost satisfies the adjacent channel power spectrum density requirement of -60 dBc specified by CCIR. The normalized pre-Gaussian bandwidth is kept at 0.3, which corresponds to a filter bandwidth of 81.25 kHz for an aggregate data rate of 270.8 Kbps. With 200 kHz of carrier spacing and this data rate, the spectral efficiency of the system is 1.35 b/s/Hz. With the bit interval of 3.7 ms, the GSM signal will encounter significant intersymbol interference in the mobile radio path due to multipath ( multipath minimal delay spread 3 ms to 6 ms in urban areas). As a consequence, an adaptive equalizer is used. There are eight time slots in a frame and 26 or 51 frames in a multiframe. With 270.8 Kbps divided among eight users in GSM, the per user data rate is 33.85 Kbps. The speech coder is a regular pulse excitation with long-term predictor (RPE-LTP) for a full rate speech that converts speech to 13 Kbps.  There are five different categories of mobile telephone units specified for the European GSM system: 0.8W, 2W, 5W, 8W, and 20W. The power level can be adjusted to vary between 3.7 mW to 20W. To optimize co-channel interference, each BS individually directs MS to use the minimum power setting that is necessary for reliable transmission. The setting is determined by BS and provided to the MS. The GSM air interface allows for frequencies to be hopped to prevent multipath problems resulting in excessive bit error rates. Both the mobile and the base station will use Discontinuous Transmission (DTx). This will allow the mobile to save the battery life and the base station to reduce co-channel interference.

Why GSM-Global System for Mobile

Why GSM

The GSM study group aimed to provide the followings through the GSM:

       ·          Improved spectrum efficiency.

       ·          International roaming.

       ·          Low-cost mobile sets and base stations (BSs)

       ·          High-quality speech

       ·          Compatibility with Integrated Services Digital Network (ISDN) and other

            telephone company services.

       ·          Support for new services.

What is GSM-Global System for Mobile Communication

What is GSM

If you are in Europe, Asia or Japan and using a mobile phone then most probably you must be using GSM technology in your mobile phone.

       #GSM stands for Global System for Mobile Communication and is an open digital  cellular technology used for transmitting mobile voice and data services. 

       #The GSM emerged from the idea of cell-based mobile radio systems at Bell Laboratories in the early  1970s. 

       #  The GSM is the name of a standardization group established in 1982 to create a common European        mobile  telephone standard.

#The GSM standard is the most widely accepted standard and is implemented globally.  

#The GSM is a circuit-switched system that divides each 200kHz channel into eight 25kHz time-slots.GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US

#The GSM is owning a market share of more than 70 percent of the world's digital   cellular subscribers.

#The GSM makes use of narrowband Time Division Multiple Access (TDMA)  technique for transmitting signals.

#The GSM was developed using digital technology. It has an ability to carry 64  kbps to 120 Mbps of data rates.

# Presently GSM support more than one billion mobile subscribers in more than 210 countries throughout of the world.

      #The GSM provides basic to advanced voice and data services including Roaming service. Roaming is

      the ability to use your GSM phone number in another GSM network.