類比通訊系統2008/11/24 金正元

Outline

• Introduction• Transmission Line• Filter• Amplifier• Mixer

Introduction

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980MHz

900MHz

Introduction

Crystal Oscillator at 100MHz and BPF

900MHz

Introduction

What’s Transmission Line?

• A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission. Components of transmission lines include wires, coaxial cables, dielectric slabs, optical fibers, electric power lines, and waveguides.

Miscellaneous Transmission Lines

Design

• 中心頻率 (980MHz)• 傳輸線結構 (microstrip

line)• 板材 (FR4)• 板子厚度 (0.8 mm)• 特徵阻抗 (50 ohm)

Design

Relative Permittivity

0

,

, 4

1

4.6

r

r air

r FR

How about microstrip line ?

, , 4r air eff r FR

Relative Permittivity

0

0

3.407

300

( , )

eff

eff eff

eff

cv f

f

f in GHz in mm

Filter

• Why do we need a filter?

Filter Types

Filter Types

Filter Types

• Maximally flat• Equal-ripple• Linear phase

Filter Types

• Lumped• Distributed

Coupled-Line Filter

Each section is 0.25 lambda long.

Coupled-Line Filter

3.407

0.98

300 141.46

4

eff

eff

f

f

4

It is very close to the practical value 42.4 !!

We can use this formula to calculate our effective relative permittivity.

Amplifier

Amplifier

• R1: bias• C1: input match• C2: output match• C3: 900MHz short• C4: RF decoupling

Layout of Amplifier

in

out

150pF

150pF

27pF

1nF

3.3k

10

150

Vcc

in

out

150pF

150pF

27pF

1nF

3.3k

10

150

Vcc

Mixer

• Mixer = Multiplier !?• Active• Nonlinear

2 30 1 2 3

1 2

y a a x a x a x

x px qx

Diode Mixer

FET Mixer

Layout of Mixer

The End

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