An Ultra-Wide-Band 1.0 - 11.6GHz LNA in 0.18µm CMOS technology RF Communication Systems-on-chip Spring 2007.

An Ultra-Wide-Band 1.0 -11.6GHz LNA in 0.18µm CMOS technology

RF Communication Systems-on-chipSpring 2007

Index of Contents

A brief introduction to UWB Potential applications

Design of the LNA Performance criteria First stage: a common-gate Second stage: a common-source

System simulation Comparison with the original paper

Conclusions

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A brief introduction to UWB

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A brief introduction to UWB

A technology for transmitting information spread over a large bandwidth that should be able to share spectrum with other users.

The Federal Communications Commission (FCC) authorized the unlicensed use of the 3.1 to 10.6GHz band under strict power restrictions.

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OFDM vs. Pulse-transmissionOFDM vs. Pulse-transmission

Potential applications

Wireless Communications Systems Local and Personal Area Networks (LAN/PAN) Roadside info-station Short range radios Military Communications

Radar and Sensing Vehicular radar Ground penetrating radar Through wall imaging Medical imaging Surveillance

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Design of the LNA6

As any Low-Noise Amplifier, an UWB LNA should have: Low noise figure (i.e., below 6dB) High gain (i.e., above 10dB) Input matching to 50Ω (i.e., S11 below -10dB) Output matching to 50Ω (i.e., S22 below -10dB)

But also, with a flat response in the whole 3.1-10.6GHz band.

Performance criteria7

Two-stage amplifier The first stage

fixes the input impedance of the system and defines a low frequency resonance.

The second stage drives the LNA total gain by fixing a second resonance in the high frequency part of the band.

Circuit description (I)8

The common-gate stage Input impedance

There is a resonance near DC. At high frequencies, gm1

becomes the dominant term.

Circuit description (II)9

1

in

1 1 11S

m gs S

sLZ

g sC sL

With RL1=320Ω, WM1=55µm and VG1=0.7V, gm1 is in the order of

20mS

With RL1=320Ω, WM1=55µm and VG1=0.7V, gm1 is in the order of

20mS

The common-source stage Defines a second resonance in

the high part of the band. Provides the gain to the system.

The output buffer was already given: WM4=55µm and Ibias=5.7mA.

Circuit description (III)10

With RL2=60Ω, WM2=WM3=120µm and VG2=1V, both transistors are

still in the saturation region

With RL2=60Ω, WM2=WM3=120µm and VG2=1V, both transistors are

still in the saturation region

Circuit simulation11

11

Circuit simulation (I)12

Effect of changing LD2

from 1nH to 3nH

Taking into account the UWB FCC mask already shown, trying to move the first resonance far below

the 3GHz is not necessary.

Taking into account the UWB FCC mask already shown, trying to move the first resonance far below

the 3GHz is not necessary.

Effect of changing LS1

from 2nH to 10nH

Gain (dB) Gain (dB)

Circuit simulation (II)13

Effect of changing VG2 from 0.6V to 1.6V

A good compromise between total gain and power consumption is achieved, for example, with 120µm

and a VG2 equal to 1.2V.

A good compromise between total gain and power consumption is achieved, for example, with 120µm

and a VG2 equal to 1.2V.

Effect of changing WM2

and WM3 from 40µm to 200µm.

Gain (dB) Gain (dB)

Final results14

L0.18μm

WM1 60μm

WM2 120μm

WM3 120μm

WM4 55μm

LS1 3.6nH

LD21.84nH

RL1 320Ω

RL2 60Ω

VG1700mV

VG2 1.2V

Design comparison15

Figure Current circuit Original circuit

Maximum Gain 13dB 12.4dB

BW-3dB 1.0-11.6GHz 0.4-10GHz

Noise Factor 3.6-4.8dB 4.4-6.5dB

IIP3 ( @ 6GHz ) -2.74dBm -6dBm

P-1dB ( @ 6GHz ) -16.27dBm -15dBm

Power consumption

15.6mW 12mW

Very similar results have been obtained.Very similar results have been obtained.

Conclusions

A two-stage LNA amplifier from 1.0 and up to 11.6GHz has been designed.

A common-gate stage fixes the input impedance of the system and creates a first resonance at low frequencies.

A common-source stage drives the system gain and introduces a resonance in the high part of the band.

A nearly flat gain of 13dB and a noise figure of 4dB are achieved within this topology.

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Thank you for your attentionRFCS. Spring 2007.

Josep Miquel Jornet Montaña [[email protected]]

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