RF circuits design 4 -...

RF circuits designGrzegorz BeziukGrzegorz Beziuk

RF characteristics of lumped passive and active elements

References[1] Tietze U., Schenk C., Electronic circuits : handbook for design and application, Springer

2008

[2] Golio M., RF and microwave passive and active technologies in: RF and Microwave

handbook, 2008, CRC Press Taylor and Francis Group

[3] Vishay, 50 GHz Thin Film Microwave Resistors, Products Data Sheet, Vishay 2009,

(www.vishay.com)

[4] AVX RF, AVX RF/Microwave products version 8.1, Products Data Sheet,

(www.avxrf.com)

[5] Panasonic, Chip inductors, Products Data Sheet,

(http://www.panasonic.com/industrial/electronic-components/inductive-products/chip-

inductors.aspx)

[6] Vishay semicondutors, BFR 93 - Silicon NPN Planar RF Transistor, Product Data Sheet,

2000, Vishay.

[7] NXP Semiconductors, BFU725F/N1 NPN wideband silicon germanium RF transistor,

Product Data Sheet, 2009, NXP Semiconductors (www.nxp.com)

References[8] Infineon Technologies, BFP 620 NPN Silicon Germanium RF Transistor, Product Data Sheet,

2004, Infineon Technologies (http//www.infineon.com/silicondiscretes)

[9] ON Semiconductors, MMBFU310LT1G JFET Transistor N−Channel, Product Data Sheet, 2009, ON

Semiconductors (www.onsemi.com)

[10] EPCOS, SAW Components, Data Sheet R 850, 2002, EPCOS, (www.epcos.com)

[11] Fabian Wai Lee Kung, RF/Microwave Circuit Design, 2008, Multimedia University, (open source

lectures: http://pesona.mmu.edu.my/~wlkung/ADS/ads.htm)

[12] Microsemi, KV1911A – KV1991A VARACTOR DIODES UHF Microwave Super-Hyperabrupt

Junction, 2007, Products Data Sheet, Microsemi

[13] Hawlett Packard, Surface mount microwave Schottky detector diodes HSMS 2850, HSMS 2860

series, Technical data, Hawlett Packard

[14] Maccom Technology Solutions, MA4AGBLP912 AlGaAs Beamlead PIN Diode, Products Data

Sheet, Maccom Technology Solutions

[15] Vishay Telefunken, BF966S N–Channel Dual Gate MOS-Fieldeffect Tetrode, Depletion Mode,

Product Data Sheet, 1999, Vishay Telefunken

[16] Murata Manufacturing, SAW resonators, Products Data Sheet, 2001, Murata Manufacturing

Resistors

Equivalent circuits SMD resistor: a) for low frequencies

range, b) for high frequencies

Resistors

( ) ( )[ ]( ) 22222

232

1 RCCL

CLRCLjRjZ

RRR

RRRRR

ωω

ωωω

+−

−−+=

Inductive properties:

Capacitive properties:

RR CLR /<

RR CLR />

Reflection factor: ( ) ( )( ) 0

0

ZjZ

ZjZj

R

RR

+

−=Γ

ω

ωω

Resistors

Impedance of SMD

resistors od the size 1206

with LR = 3nH, CR = 0.2pF

* Taken from „Electronic circuits : handbook for design and application” Tietze U., Schenk C. [1]

Resistors

Typical very high frequency performance electrical model

The external reactance (Lc and CG) depends on the PCB material, the layout and

assembly technology.

Resistors

Impedance as a function of frequency for a chip resistor N termination (wraparound)

* Taken from „50 GHz Thin Film Microwave Resistors”, Products Data Sheet, Vishay [3]

Resistors

Impedance as a function of frequency for a chip resistor (F and P terminations)

* Taken from „50 GHz Thin Film Microwave Resistors”, Products Data Sheet, Vishay [3]

Capacitors

Equivalent circuits SMD capacitor: a) for low frequencies


Capacitors

sC

CLssCRsZ CC

C

21)(

++=

C

L

RQ

CLf

C

C

res

C

res

1

2

1

=

=π

( ) ( ) ( ) C

ff

C

CC

fCRfjZ

fjZfQ

res

ππ

π

2

1

2Re

2Im4/

≈=<

Impedance of capacitor:

Resonant frequency:

Quality factor (QF):

CapacitorsMagnitude of

impedance for SMD

capacitors of size 1206

with RC = 0.2Ω, LC =

3nH


Capacitors

* Taken from „AVX RF/Microwave products version 8.1”, Products Data Sheet, AVX RF [4]

Example of parameters of the high frequency capacitors

Chip Inductors

Equivalent circuits SMD inductors: a) for low frequencies


Chip Inductors

( ) fkfR RLL =

Lkk LRL ≈

( )HHzkL ⋅Ω≈ /1200

( )HHzkL ⋅Ω≈ /600

(skin effect!!!)Parasitic resistance

Resistive losses coefficient

For 1206 size inductor:

For 1812 size inductor:

For inductors larger than 1812 size, and L>10µH : ( ) 7.0/20 LHzkRL Ω≈

Chip Inductors

4

32

2

1

LRL

res

L

res

C

L

kQ

LCf

π

π

=

=

4max

2

2

11

11

res

resres

res

resresph

Qff

Qff

−≈

−≈

Resonant frequency:

Phase resonant

frequency

Magnitude resonant

frequency

(an impedance of inductor

has a real value)

Quality factor (QF): ( ) ( ) ( ) ( )

fk

L

fR

fL

fjZ

fjZfQ

RLL

ff

L

LL

res ππ

π

π 22

2Re

2Im4/

=≈=<

Chip Inductors


Magnitudes of impedance and

inductor quality for SMD inductors of

size 1206 with ( )HHzkL ⋅Ω= /1200

and CL=0.2pF

Chip Inductors

* Taken from „Chip inductors”, Panasonic Products Data Sheet, [5]

Chip Inductors

* Taken from „Chip inductors”, Panasonic Products Data Sheet, [5]

ChokesChoke is a kind of inductor. Chokes are used below 2 GHz,

but there are some chokes applications extends to tens of

GHz.

Chokes:

- for high frequency are high impedance elements

- for low frequency and direct current have very little loss

Chockes are use in the bias circuits of active elements.

Because the choke is an inductors with ferrite core, for high

frequency (f>2GHz) its resonances are absorbed by losses in

a ferrite.

Ferrite BalunsFerrite balluns are cross between transmission lines and chokes.

Ferrrite baluns are most useful between 10 kHz and 2 GHz.

Manufacturers desigh baluns for specific impedance levels and

bandwitdths.

SAW filtersBasic structure of Surface Acoustic

Wave (SAW) resonator

* Taken from „SAW resonators”, Murata Manufacturing Products Data Sheet, [16]

1-port SAW RESONATOR has one IDT

(Inter Digital Transducer), which generates

and receives SAW, and two grating

reflectors, which reflect SAW and generate

a standing wave between the two

reflectors. IDT and reflectors are fabricated

on quartz crystal substrate by

photolithographic process. Frequency

range: from 50kHz 1GHz.

SAW filtersFeatures of the SAW:

- high Oscillation Frequency Stability

- adjustment free - SAW resonator is stable against

peripheral circuit or supply voltage fluctuation

- simple/low cost circuit by fundamental oscillation -

oscillates with its fundamental mode

- small size package

- they can be applied Colpitts Oscillator circuit

SAW filters

SAW equivalent circuit


SAW filters


Caoxial Cablesd

D

ε

RLCG parameters:

( )

( )

( )dDG

dDC

dDL

dDR

j

/ln

''2

/ln

'2

/ln2

111

'''

πωε

πε

π

µ

πσδ

εεε

=

=

=

+=

−=

( )

≈==

d

DdD

C

LZ

reff

ln60

/ln'2

10

εε

µ

π

For R=0, G=0:

Zo = 50, 75, 93 Ω.

Caoxial Cables

Cut-off frequency:

dDf

reff

offcut+

=−

151.7

ε

Velocity of propagation:

reff

p

cv

ε=

Maximum peak power:( )

( )2

2

2

max/

/ln

480

max

dD

dDD

EP =

Caoxial Cables

* Taken from „Introduction to high-speed PCB design”, Kung [11]

Caoxial Cables

Why 50Ω?


Caoxial Cables


Connectors and Adapters





502.4 mm

462.9 mm

26.53.5 mm

18SMA

187 mm

18Type-N

15TNC

10SMC

4SMB

(0.3) 4BNC

Cut-off frequency [GHz]Connector type

VaractorsVaractors applications:

- harmonic generation

- parametric amplification

- mixing

- detection

- voltage variable tuning

Advantages of varactors:

- low loss

- low noise

Non-symetric

Symetric

Varactors

Example of varactors characteristics

* Taken from „KV1911A – KV1991A VARACTOR DIODES”, Microsemi [12]

Schottky diode

Schottky diode (metal-semiconductor juntion) applications:

- harmonic generators (mutipliers) GHz and THz

- mixers

- detectors

In frequency mutliplication is used a nonlinear capacitans versus

voltage.

Schottky diode

* Taken from „Surface mount microwave Schottky detector diodes HSMS 2850, HSMS

2860 series”, Hawlet Packard [13]

PIN diodesPIN diodes applications:

- RF and microwave attenuators

- RF and microwave tunable matching circuits

- RF and microwave switches

PIN diodes

* Taken from „MA4AGBLP912 AlGaAs Beamlead PIN Diode”, Maccom Technology

Solutions [14]

Bipolar junction transistors (BJTs)

P N

IC

N

- +UCB

- +UBE

ColectorEmmiter

Base

IE I

B


- HF bipolar transistors are NPN type because electron

mobility is much higher than hole mobility

- the BASE thickness is very thin to improve current gain β(hfe)

- Inter-digital BASE and EMITTER contacts are employed

to reduce base spreading resistance rbb’ and to reduce the

noise generated by the transistor

- Commercial RF transistors in discrete form can have fT up

to 10GHz.


Bias circuits of BJT – read the textbooks about basics of an electronic

circuits




B C

E

rCE

rB'E

B'rbb'

cB'E

cB'C

gmUB'E

B C

E

rCE

rB'E

B'rbb'

cB'E

cB'C

gmUB'E

„Hybrid π” (Giacoletto) model of the BJT.


T

CQ

EB

Ir

ϕ

β='

T

CQ

m

Ig

ϕ=

CQ

EYCE

I

Ur =

m

DC

CBCBCB

U

Ucc

−

−= 10''

T

m

TT

CQ

EB

g

f

Ic

ωϕπ==

2'

Hybrid π model elements.

For frequencies above 300 MHz transistor

should be modelled by ‘S’ parameters.



* Taken from „BFP 620 NPN Silicon Germanium RF Transistor”, Product Data

Sheet, 2004, Infineon Technologies [8]

Example of HF

package

equivalent circuit

of BJT BFP 620


* Taken from „BFR 93 - Silicon NPN Planar RF Transistor”, Product Data Sheet,

2000, Vishay [6]



2000, Vishay [6]



2000, Vishay [6]

FET

n p+p+

Drain

Source

Gate Gate

D

G

SN-channel FET

FET

n p+p+

+

-

UGS1

+

-

UDS=0.1V

p+p+

+

-

UGS2

+

-

UDS=0.1V

n

UGS1

< UGS2I

DID

barrierlayer

barrierlayer

FET

n p+p+

+

-

UGS1

+

-

UDS=10V

p+p+

+

-

UGS2

+

-

UDS=10V

n

UGS1

< UGS2I

DID

barrierlayer

barrierlayer

FET

Bias circuits of FET and FET with P chanel – read the textbooks about

basics of an electronic circuits

MOSFET

n

p+

DrainSource

Base

Gate

p+

SiO2

p

n+

DrainSource

Base

Gate

n+

SiO2

p p

p

n+

DrainSource

Base

Gate

n+

SiO2

n

p+

DrainSource

Base

Gate

p+

SiO2

There are the MOSFET with two gates, too.

MOSFET

UGS

D

G

S+

-

UGS

D

G

S

ID

ID

UDS=0.1V U

DS=10V

n+

n+

SiO

2

p

n+

n+

SiO

2

p

+

-

+

-

+

-

N-channel MOSFET

MOSFET

Bias circuits of MOSFET and more information about other types of

MOSFETs – read the textbooks about basics of an electronic circuits

FET and MOSFET

FET and MOSFET „hybrid π” model

FET and MOSFET

FET and MOSFET

* Taken from „ BF966S N–Channel Dual Gate MOS-Fieldeffect Tetrode, Depletion

Mode”, Product Data Sheet”, 1999, Vishay Telefunken [15]

FET and MOSFET



FET and MOSFET



FET and MOSFET



FET and MOSFET



Other types of RF and microwave

transistorsThere are other types of the microwaves

transistors:

- Heterostructure Bipolar Transistor (HBTs)

- High Electron Mobility Transistor (HEMT)

They are commercialy avaible such as the discrete

elements. They are integrated in microwave IC

such as i. e. LNA, power amplifiers.

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