Paper presentation Ultra-Portable Devices Paper: F Bruccoleri, E - - PowerPoint PPT Presentation

Paper presentation – Ultra-Portable Devices

Paper: Presented by:

F Bruccoleri, E Klumperink, B Nauta ”Generating All Two-MOS-Transistor Amplifiers Leads to New Wide-Band LNAs” Journal of Solid State Circuits, vol. 36, no. 7, pp. 1032- 1040, july 2001.

Carl Bryant

2010-02-22 1 Paper Presentation - Ultra Portable Devices

Outline

• Introduction
• Systematic approach
• Generate combinations
• Parameter analysis
• Amplifier selection
• Amplifier analysis
• LNA

2010-02-22 2 Paper Presentation - Ultra Portable Devices

Introduction

• Design wideband LNA
• UWB requires inductorless design
• Should present real impedance
• Should have gain
• Should have low noise
• Idea:
• Systematic design
• Explore all combinations of two transistors

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Systematic approach

• Generate all two device combinations

– MOS devices represented as voltage controlled current source (vccs) – Combined devices represented using two-port representation

• Select potentially useful amplifiers
• Examine amplifiers

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• Create two-port represented by ABCD parameters

Generate combinations

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                     

2 2 1 1

i v D C B A i v

Two-port network + v1

• +

v2

• i1

i2

Parameter analysis

• Potentially useful

– Has forward gain – Presents real input impedance – Wideband (> one decade) – Stable

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Parameter analysis

• Find constraints
• Study ZIN and AVF as function of ZL and ABCD parameters

– ZIN & AVF different from {0,} – At least two parameters nonzero

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Parameter analysis

• Non-zero parameter combinations

– Example: AD represents {A,0,0,D}

• Assume ZL = 1/jωCL
• {AD} and {BC} cases too frequency dependent
• {BD} and {BCD} show frequency dependent gain
• {ABD} cannot provide simultaneous wideband match and gain

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Parameter analysis

• Sought two-ports contained in:

{AC, ABC, ACD, ABCD}

• Want unconditional stability
• (ZIN)0, (Z22)0

assuming Z11=ZIN

• Neccesary and sufficient {A,B,C,D} have same sign

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Amplifier selection

• Implementable with MOS devices

– Only select circuits where vccs form three terminal devices – Of 145 2VCCS combinations 19 remain – Correspond to {ACD, ABC, ABCD} cases

• One {ABC} and three {ABCD} fulfill all requirements

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Amplifier analysis

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ZIN ZOUT A

VF

A

VR

Amp1 1/ga 1/gb 1+ga/gb Amp2 1/ga 1/ga

• ga/gb

gbRS Amp3 1/ga (Rb+RS)/(1+gaRS) 1-gaRb gbRS/(gaRS+1) Amp4 1/ga Rb gaRb

No comment

NEF = Noise Excess Factor (related to )

Amplifier analysis

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Amplifier analysis

• Amp 1:
• NF independent of gain
• VCCSa noise cancelled

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LNA

• Based on Amp1
• Variable gain by changing gb

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LNA

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Performance Summary Vdd 3.3V Idd 1.5 mA Tech. 0.35 μm AVF 11 dB

• 3dB BW

50-900 MHz CP1dB

• 6 dBm

IIP3 14.7 dBm NF <4.9 dB RS 75 Ω

Summary

• Systematic design of compound amplifier stage
• Result is new LNA structure
• Promising noise & linearity
• 2dB better NF than comparitive CG amplifier
• Low current consumtion for 0.35μm design

– Scales to 375μA @ 300Ω

• Such a stage used in december tape-out

2010-02-22 16 Paper Presentation - Ultra Portable Devices