Sparameters and noise figure of a twostage LNA in SiGe BiCMOS 0'35m technology

1
S-parameters and noise figure of a two-stage LNA
in SiGe BiCMOS 0.35µm technology
1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008

• Alena Ðugova
• Mirjana Videnovic-Miic
• Faculty of Technical Sciences,
• Department for Power, Electronics and
  Communications Engineering,
• Novi Sad

2
OVERVIEW

• Introduction
• LNA design consideration
• LNA architecture
• Simulation results
• Conclusion

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
3
INTRODUCTION

• LNA - the key component in a typical wireless
  receiver
• minimum noise
• high gain
• low power consumption
• good impedance matching

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
4
LNA DESIGN CONSIDERATION

• finding the most appropriate LNA architecture
• selection of the LNA operating frequency range
• choosing appropriate input matching circuit in
  order to achieve maximum power transfer

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September 2008
5
LNA topologies

• single-ended
• higher gain in case of the same current
  consumption
• better noise performance

• differential-ended
• immunity against interference
• higher common mode rejection ratio

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September 2008
6
LNA operating frequency range

• broadband
• allows the LNA to be used at any frequency in its
  amplification band
• too much expensive in term of power dissipation
• difficult to satisfy the input impedance
  requirement in broadband realization
• narrowband
• provides near optimum gain and noise figure while
  providing a real input resistance
• drawback requires the use of inductors with high
  Q inductors (difficult to achieve)

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
7
Typical LNA Input Matching Networks

• (a) resistive termination of the input port to
  provide 50O input impedance
• broadband input matching provides a perfect input
• matching
• seriously degrades the LNA NF
• (b) the source of a common-gate MOSFET as an
  input termination
• input impedances seen from the source is the
  inverse of the transconductance (1/gm)
• sufficient to correctly design the MOSFET and its
  DC current to provide a good, wideband input
  matching
• minimum NF is inversely proportional to the
  channel length
• of the MOSFET

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
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Typical LNA Input Matching Networks

• (c) resistive shunt and series feedback to set
  the input and output impedances
• have extraordinarily high power dissipation
  compared to amplifiers with similar noise
  performance (broadband)
• requires on-chip resistors of reasonable quality
• (generally not available in CMOS technologies)
• (d) inductive source degeneration to generate
• a real term in the input impedance
• provides, at a given frequency, the correct real
  input
• impedance without the introduction of resistors
  (RS?TLS )
• the NF is only degraded by the parasitic
  resistances
• associated to integrated spiral inductors LS and
  LG
• narrowband approach

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
9
LNA ARCHITECTURE

• two-stage narrowband LNA

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008
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SIMULATION RESULTS

• fixed-PD noise optimization technique for
  starting simulation data D. K.Scheffer and T.
  H.Lee, A 1.5-V, 1.5-GHz CMOS low noise
  amplifier
• operating frequency f01.57542GHz (GPS)
• LNA simulated using the Cadence Spectre simulator
• LNA designed in austriamicrosystems 0.35µm SiGe
  BiCMOS technology
• components real models (austriamicrosystems) were
  used, except for Ls (too small value, not given
  by austriamicrosystems)

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September 2008
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SIMULATION RESULTS
S11_at_1.57542GHz-36.44dB
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12
SIMULATION RESULTS
S22_at_1.57542GHz-30.84dB
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SIMULATION RESULTS
S21_at_1.57542GHz40.14dB
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SIMULATION RESULTS
S12_at_1.57542GHz-58.81dB
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September 2008
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SIMULATION RESULTS
NF_at_1.57542GHz1.386dB
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September 2008
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CONCLUSION

• results satisfied general requirements
• S11-36.44dB lt-10dB
• S22-30.84 lt-10dB
• S2140.14dB gt20dB
• S12-58.81dB
• NF1.386dB lt3dB
• next steps
• real model for LS
• stability issues

1st ReCIMiCo WORKSHOP, Novi Sad 29th and 30th
September 2008