Chapter2 System Parametters and Transciever Architectures 1.pdf

7/24/2019 Chapter2 System Parametters and Transciever Architectures 1.pdf

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Cuong HuynhTelecommunications DepartmentHCMUT1

Huynh Phu Minh [email protected]

Department of Telecommunications

Faculty of Electrical and Electronics Engineering

Ho Chi Minh city University of Technology

Chapter 2System Parameters and Transceiver Architectures

MICROWAVE INTERGRATED CIRCUITS
mailto:[email protected]:[email protected]


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1 Noise and Nonlinear Distortion in Microwave Systems

Noise in Microwave System


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Thermal noise is the most basic type of noise, being caused by thermal vibration

of bound charges. It is also known as Johnson or Nyquist noise.

Shot noise is due to random fluctuations of charge carriers in an electron tube or

solid-state device.

Flicker noise occurs in solid-state components and vacuum tubes. Flicker noisepower varies inversely with frequency, and so is often called 1/ fnoise.

Plasma noise is caused by random motion of charges in an ionized gas, such as a

plasma, the ionosphere, or sparking electrical contacts.

Quantum noise results from the quantized nature of charge carriers and photons;

it is often insignificant relative to other noise sources.


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Noise Figure


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2.1 Noise and Nonlinear Distortion in Microwave Systems

Noise Figure




Noise Figure

3

n

is the noise factor in linear (not in dB) of the n-th stage,

G is the power gain in linear (not in dB), too.

nNF

-1




Sensitivity


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Required Receiver SensitivityA Qualitative View

To find Receiver NF Transmit PowerFCC

regulated

Path loss Receiver sensitivitygovern

by standards and applications

Required SNRdepends onBER requirement andmodulation scheme

Noise floorthermal noise orcircuit noise limiteddepending on the modulationschemes

What is the required receiver NF to achieve

a certain level of sensitivity?

Transmit Power

Input Noise Floor (No/G)Required SNRo

Noise Figure

Path Loss

Receiver Sensitivity

Input Noise (Ni)




Nonlinear Distortion

Harmonic generation (multiples of a fundamental signal)Gain Compression (gain reduction in an amplifier)

Inter-modulation Distortion (products of a two-tone input

signal)

Cross-modulation (modulation transfer from one signal toanother)

AM-PM conversion (amplitude variation causes phase shift)

Spectral regrowth (intermodulation with many closely spaced

signals)

vi Taylor series: f(x)=vo




Nonlinear DistortionHarmonic Generation and Gain Compression




Nonlinear DistortionDesensitization and Blocking




Nonlinear DistortionInter-modulation Distortion

Consider a two-tone input voltage. These combinations of the two inputfrequencies are called intermodulation products (IMP)




Nonlinear DistortionInter-modulation Distortion




Nonlinear DistortionInter-modulation Distortion (IMD)



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Input IP is the point where

the output power at 1equals

to output power at (21 - 2 )

3rd order intercept point : IP3



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Determine IP3 by Spectrum Measurement



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Nonlinear DistortionSFDR)


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Nonlinear DistortionSFDR)

Prove ?

2 2 R i A hit t


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2.2 Receiver Architectures

Receiver Architecture

Receiver basics

Channel selectionwhy not at RF?

BPF first or LNA first?

Receiver architectures

Heterodyne receiverimage problem

Super-heterodyne receivermore image problem

Image-reject receivers

Harley receiverWeaver architecture

Homodyne (direct conversion, zero-IF)DC offset

Digital IF

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Fundamental Trade-off in Receiver

Using one or more IF stages to relax the filter

requirements, but need to deal with images

Using image reject mixers with I&Q LO signals to

eliminate the need of band-pass filters (to enable higher

level of integration)

RF ICs typically employ a combination of simple mixing

with some image filtering and image reject mixing

2 2 R i A hit t


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2 MHz

2 2 R i A hit t


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2 2 Recei er Architect res


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Ta thay tin hieu lon hon va cao hon do duoc khuech dai truoc khi tron tan

2 2 Receiver Architectures


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Neu tin hieu doi xung nhau, sau khi doi tan xuong thi tin hieu se chong

chap len nhau lon hon tin hieu ban dau.

Neu tin hieu khong doi xung sau khi doi tan no se chong lan len

h huy tin hieu ban dau



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. ece ve c tectu es

2.3 Transmitter Architectures


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DECT: Digital Enhanced

Cordless Telecommunications



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SAW: Surface Acoustic Wave

http://en.wikipedia.org/wiki/Surface_acoustic_wavehttp://en.wikipedia.org/wiki/Surface_acoustic_wave


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Chapter2 System Parametters and Transciever Architectures 1.pdf

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