“Mixed Signal VLSI DESIGN: Basics of CMOS

Analog, Digital and RF Circuits”

Arun N. Chandorkar

Department of Electrical Engineering

Indian Institute of Technology, Bombay

Powai, Mumbai-400076,India

E-Mail: anc@ee.iitb.ac.in

16th March 2009

Mixed Signal Basics

OUTLINE:

• 1.Technology

• 2. Analog Design issues

• 3. Digital Design Blocks

• 4. RF design issues

• 5. Components

• 6. Conclusion

“Mixed Signal VLSI DESIGN”

Basics of CMOS Technology

16th March 2009

CMOS Process sequence for Mixed Signal Circuits

Reference: CMOS Mixed Signal Design : R.J.Baker

CMOS Process sequence for Mixed Signal Circuits

Reference: CMOS Mixed Signal Design : R.J.Baker

“Mixed Signal VLSI DESIGN”

Basics of CMOS Analog Circuits”

16th March 2009

“Mixed Signal VLSI DESIGN: Basics Blocks of CMOS Digital

Circuits”

Reference: CMOS Mixed Signal Design : R.J.Baker

“Mixed Signal VLSI DESIGN”

Basics of CMOS RF Circuits

16th March 2009

RF VLSI Design: Issues and Applications

Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world.GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM networks operate in four different frequency ranges. Most GSM networks operate in the 900 MHz or

1800 MHz bands. Some countries in the Americas (including Canada and the United States) use the 850 MHz and 1900 MHz bands because the 900 and

1800 MHz frequency bands were already allocated.The rarer 400 and 450 MHz frequency bands are assigned in some

countries, notably Scandinavia, where these frequencies were previously used for first-generation systems.

In the 900 MHz band the uplink frequency band is 890–915 MHz, and the downlink frequency band is 935–960 MHz. This 25 MHz bandwidth is

subdivided into 124 carrier frequency channels, each spaced 200 kHz apart. Time division multiplexing is used to allow eight full-rate or sixteen half-rate

speech channels per radio frequency channel. There are eight radio timeslots (giving eight burst periods) grouped into what is called a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data

rate is 270.833 kbit/s, and the frame duration is 4.615 ms.

RF Systems for VLSI Design

RF Systems ( Continued)Code division multiple access (CDMA) is a channel access method utilized

by various radio communication technologies.W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular

network. W-CDMA is the higher speed transmission protocol used in the UMTS system.

Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) cell phone technologies. Currently, the most common form

uses W-CDMA .Wi-Fi is a Wireless technology brand owned by the Wi-Fi Alliance intended to

improve the interoperability of wireless.WiMAX, the Worldwide Interoperability for Microwave Access, is a

telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is based on the IEEE 802.16 standard, which is also called

WirelessMAN..A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum

or OFDM modulation technologyDCS1800 - Digital Cellular System 1800MHz. Digital Cellular System 1800MHz

is a term given to what is now known as GSM1800

RF Design Issues

• Linearity• Dynamic Range and Power Distortion• Noise• Impedance matching• Modeling of devices at RF frequencies• Temperature dependence• Modeling of passive components• Matching between the components• Power consumption• High frequency figure of merit, fT should be at least five times higher

than the operating frequency

RF Design Hexagon

Large Signal Issues ( Cont.)

“Mixed Signal VLSI DESIGN”

Basics Circuit Components in CMOS Technology

16th March 2009

Low Frequency C-V of MOS capacitor

Reference: CMOS Mixed Signal Design : R.J.Baker

Floating MOS Capacitor

Reference: CMOS Mixed Signal Design : R.J.Baker

Reference: CMOS Mixed Signal Design : R.J.Baker

Reference: CMOS Mixed Signal Design : R.J.Baker

Reference: CMOS Mixed Signal Design : R.J.Baker

Resistors Realization in CMOS Technology

Spiral Segment of Inductor on Si

Inductors in MOS Technology• The self-inductance for a straight conductor is L =ln { 2l /GMD} -1.25 + (AMD/l) + (

Where L is the self-inductance in micro henries, l is the conductor length in cm, GMD and AMD represent the geometric and arithmetic mean distance, respectively,

of the conductor cross section, is the conductor permeability, and T is the frequency correction parameter.

• The geometric mean distance (GMD) between two conductors is the distance between two infinitely thin imaginary filaments whose mutual inductance is equal to the mutual inductance between the two original conductors .

The GMD is equal to 0.44705 times a side in the case of a square cross section.

• The arithmetic mean distance (AMD) is the average of all the distances between the points of one conductor and the points of another. For a single conductor, the arithmetic mean distance is the average of all possible distances within the cross section.

Variation in Frequency-Correction Parameter T

Table.1 Thin Films and Microwave Frequencies.

Value of T Film Thickness Frequency

0.9974 10000 A 10 gigahertz

0.9986 0.0025 mm 1 gigahertz 0.9095 0.0075 mm 1 gigahertz

Inductance of spiral

• M = 2 l Q where Q=ln[(1/GMD) + sqrt {1+ (l2 / GMD2)}] – sqrt { 1+ (GMD2 / l2) } + (GMD/l)

• Total Inductance is then given by:

LT = L0 + M + + M –

where L0 is the sum of the self-inductances of all straight segments,

M + is the sum of the positive mutual inductances and

M – is the sum of th negative mutual inductances

Spiral Inductor

Physical Inductor Model

Mutual inductanceZin = j w (L+M)

which means the inductance of the conductor increases by M, and M is the mutual inductance between the two conductors.

So, parallel currents traveling in phase’ can contribute positive

mutual components of inductance.

Thus the inductance of a conductor can be expressed as,

L = Lself ± M

M = 2 l Q where

Q=ln[(1/GMD) + sqrt {1+ (l2 / GMD2)}] – sqrt { 1+ (GMD2 / l2 } + (GMD/l)

LT = L0 + M + + M -

Layout of Spiral inductor and probe pads for measurement.

RF inductor issues

AcknowledgementsTO

My Graduate students of last 10 Years,Who did their Projects

With me in Analog, Digital and RF Designs&

Also those who participated in my courses in“Digital VLSI Design”, “Analog VLSI Design”

VLSI technology, RF VLSI and System Design.Thanks to authors who put their work on

Many Websites and they are as referred in the PPTs

Thank-you