Design Considerations for 60ghz Cmos Radios

8/13/2019 Design Considerations for 60ghz Cmos Radios

1/21

DESIGN CONSIDERATIONS

FOR 60GHz CMOS RADIOs

11/23/2013

1


2/21

I. CONTENTS:

11/23/2013

2

1. INTRODUCTION

2. RADIO ARCHITECTURE

3. MILLIMETER-WAVE ACTIVE & PASSIVE

ELEMENTS4. KEY RF BUILDING BLOCKS

5. CONCLUSION

6. REFERENCES


3/21

II. INTRODUCTION

11/23/2013

3

The advances over the past fully integrated RF CMOS transceivers a reality.

Drawback of using below 10GHz range is that it will be over congested innear future.

In July 2003 the IEEE 802.15.3 working group for WPAN beganinvestigating the use of the 7 GHz of unlicensed spectrum around 6O GHz.

Alternate physical layer for high-data rate applications.

Targeted data rate is 2Gb/s.

Difficulties: high path loss, limited to short distance range


4/21

11/23/2013

4

In order for 60 GHz wireless systems to have mass deployment andmeet consumer market- place requirements, the cost and size of anysolution has to be significantly low than the current deployment.

Digital CMOS technology is the lowest-cost option, and with its rapidimprovement due to continual scaling.

CMOS technology is becoming a viable option to address the mm-wavemarket.


5/21

III.RADIO ARCHITECTURE

11/23/2013

5

3.1 ANTENNA ARRAYS: Disadvantage of a 60 GHz radio is the small antenna capture

area .

Friis propagation loss is given by:

Fortunately, the antenna directivities D1,2 can be improved.

For a fixed antenna aperture size A the directivity is

improvement in the received power by moving to higher

frequencies. For example, a 60 GHz system with a 16-element antenna array

has 3 dB gain over a 5 GHz system.


6/21

3.2 TRANSCEIVER ARCHITECTURE:

11/23/2013

6

A generic adaptive beam forming multiple antenna radio system isshown in Figure 1.

The main benefit of the multi-antenna architecture used here is theincreased gain the directional antenna pattern provides.

In addition , also provides spatial diversity, automatic spatial powercombining, and electronic beam steerability.

Flexible multi-input multi-output (MIMO) system.

The main drawback is the high transceiver complexity and powerconsumption since there is little sharing of the hardware components.


7/21

FIGURE 2:

11/23/2013

7


8/21

3.3 PACKAGING:

11/23/2013

8

For an antenna array, N transceivers (about 10) will need to beintegrated into a low-cost mm- wave package.

Low-temperature co-fired ceramic (LTCC) substrates offer a promisingpackaging option due to their low cost and good mm-waveperformance.

Low-loss transmission lines and efficient antennas operating at mm-

wave frequencies have been demonstrated on LTCC by researchers .


9/21

IV.MILLIMETER-WAVE ACTIVE AND

PASSIVE ELEMENTS

11/23/2013

9

4.1 MILLIMETER-WAVE TRANSISTOR DESIGN: Reducing parasitic capacitance improves performance .

However, at mm-wave frequencies resistive losses due to transistor

and layout parasitics play an increasingly important role since theydissipate power that cannot be restored.

This limitation is best captured by the maximum frequency of

oscillation (fmax) figure of merit, which is the maximum frequencyat which the device remains active.


10/21

4.1 MILLIMETER-WAVE TRANSISTORDESIGN:

11/23/2013

10

The value of fmax is not only determined by sizing and bias conditions,but is also highly dependent on these resistive parasitics.

As mentioned, fmax is limited by resistive losses, the most significantbeing the gate resistance (RG), series source/drain resistances (RS,RD), non-quasi-static channel resistance (rnqs), and resistive substratenetwork (Rsb, Rdb, and Rbb).

By proper layout, the fmax of an NMOS transistor in a standard 130 nm

CMOS technology can easily surpass 100 GHz.


11/21

FIGURE 3:

11/23/2013

11


12/21

4.2 TRANSMISSION LINES:

11/23/2013

12

Compared to spiral inductors commonly used for RF circuits, transmissionlines are better suited to accurately realize the small inductors required at thesefrequencies.

inherent scalability provided by the quasi-transverse electromagnetic (quasi-TEM) fundamental mode of propagation, greatly simplifies compact modeling

and simulation. Although transmission lines at lower frequencies are lossy and consume

significant die area, at 60 GHz typical transmission line lengths are less than200 m.

Inductive effects of interconnect wiring cannot be neglected. However, if theinterconnects are implemented using transmission lines, all distributed effects

will be taken into account.

Another benefit of using transmission lines is that the well defined groundreturn path significantly reduces magnetic and electric field coupling toadjacent structures.


13/21

V. KEY RF BUILDING BLOCKS

11/23/2013

13

Furthermore, accurate device models enable predictable frequencyresponse and distortion performance.

Allowing the circuit designer to fully exploit the capabilities of thetechnology.


14/21

5.1 AMPLIFIERS:

11/23/2013

14

A wideband general-purpose 60 GHz amplifier has been designed.

A die micrograph of the three stage amplifier is shown in Fig.

Gain stages consisting of NMOS common source cascode amplifiers areused to reduce the Miller capacitance.

CPW(coplanar waveguide) transmission lines are used extensively.


15/21

FIGURE 1:

11/23/2013

15


16/21

5.2 MIXERS:

11/23/2013

16

Mixers are of critical importance in transceivers.

In the mm-wave region, it is difficult to obtain high-gain CMOS low-noise amplifiers.

Simpler architectures are preferred.

A single-gate mixer is also a transconductance mixer, as the time-varying gm(t) of the common-source stage is the main source of

frequency conversion.


17/21

5.3 LOCAL OSCILLATORS:

11/23/2013

17

Fundamental-mode and push-push VCOs can be employed.

Phase noise of the oscillator is limited by Q of varactor.

DC power consumption is not the primary concern.

It becomes increasingly difficult to meet large tuning range and high-Q without introducing parasitics.

Another approach, commonly used in mm- wave systems, is to use alower-frequency LO in conjunction with a frequency multiplier.


18/21

5.4 POWER AMPLIFIERS:

11/23/2013

18

CMOS scaling exacerbates the difficulty of generating sufficient outputpower at the transmitter.

Novel circuit topologies for power combining may be required.

Another approach is to use a spatial power combining scheme.


19/21

VI.CONCLUSION

11/23/2013

19

The feasibility of a CMOS wireless Transceivercapable of 6O GHz operation has beeninvestigated.


20/21

REFERENCES:

11/23/2013

20

1. Design Considerations for 60 GHz CMOS Radios by Chinh H. Doan,Sohrab Emami, David A. Sobel, Ali M. Niknejad, and Robert W.Brodersen, Berkeley Wireless Research Center, 0163-6804/04/ 2004IEEE

2. IEEE 802.15 Working Group for WPAN; http://www.ieee802.org/15/3. M. R. Williamson, G. E. Athanasiadou, and A. R. Nix,Investigatingthe

Effects of Antenna Directivity on Wireless Indoor Communication at 60GHz,8th IEEE Intl. Symp. PIMRC, Sept. 1997, pp. 63539.4. S. Reynolds et al., 60GHz Transceiver Circuits in SiGe Bipolar

Technology, IEEE Intl. Solid-State Circuits Conf. Dig. Tech. Papers,Feb. 2004, pp. 44243.

5. C. H. Doan et al., Design of CMOS for 60GHz applications, IEEEIntl. Solid-State Circuits Conf. Dig. Tech. Papers, Feb. 2004, pp. 44041.

6. A. Yamada et al., 60GHz Ultra Compact Transmitter/Receiver with aLow Phase Noise PLL-oscillator,IEEE MTT-S Intl. Microwave Symp.Dig., June 2003, pp. 203538.


21/21

11/23/2013

21

THANK YOU!

Documents

Design Considerations for 60ghz Cmos Radios