radio frequency engineering lecture #1 passives - extra stepan lucyszyn...

Radio Frequency EngineeringLecture #1 Passives - Extra

Stepan Lucyszynステファン・ルシズィン　インペリアル・カレッジ・ロンドン准教授

Lecture #1

Passives – Extra



RF Inductors

Printed Spiral

Inductor

Straight narrow wire or PCB track

Coil on former

with slug tunerCoil



10 MHz – 40 GHz conical inductor, ~ 2.2 mm long

Full of EM absorber

VERY

LOSSY!!



RF Capacitors

4p7

Ceramic

Polystyrene

Polyester

TrimmerSurface mount

Single layer chip



“Opti-CapTM Broadband SMD Capacitor DC to Light”Dielectric Laboratories Inc.

Ultra-Broadband DC Blocking Capacitors

Small capacitor in parallel with large capacitor,

Plus resistive damping of resonances



RF Resistors



Grounding methods: (a) through-substrate via-holes, (b) wrap-around grounding and (c) bond-wires

MIM capacitor

Metalised lower ground plane

GaAs substrate

Via hole Metalised lower ground plane

GaAs substrate

MIM capacitor

Gold-plated chip carrier

GaAs substrate

(a) (b)

(c)



Through-substrate vias are difficult to realise with brittle substrates (e.g. silicon, GaAs, alumina, etc.) and have reliability implications. Up to ~20 GHz, they can be modelled with a simple series R-L circuit.

Wrap-around grounds have reduced inductance. However, they require an edge metalisation process and they still impose severe restrictions on the topology of the circuit.

Bond wires have relatively high inductance (e.g. ~1 nH/mm with 25 m diameter wires). Therefore, multiple wires are needed, which must be kept as short as possible. Moreover, they impose severe restrictions on the topology of the circuit, since they have to be located near the edge of the MIC. This type of grounding can be modelled with a fringe capacitance in parallel with the inductor.



l

Lj

l

R

l

Z HFHF

Rwidth

llengthL oo

HF

2,

,

2

mmmLR

mmpHL

mm

HFHF

ooHF

o

o

ooo

/119

/192/10252

10

2

368.21014.22

1

2

6

3

9

Simplified Bond Wire Modelling

Given a gold bond wire, having a bulk DC resistivity of 22.14 n.m and 25 m diameter, calculate the skin depth, the internal HF inductance per millimetre and HF resistance per millimetre at 3.6 GHz.

Ignoring a factor that accounts for the shape (length over diameter) of the wire!

a factor of ~ 40 too low

about right



Bare-chip device and typical parasitics

Microstrip

Hole through to ground, with gold plated chip carrier insert

g d s

End effect capacitance of the microstrip ~ 0.02 pF

Bond pads ~ 0.04 pF each

Bond wires ~ 0.8 nH per mm length



Interconnect stack in the Intel 130nm P860 technology



There are three quite distinct circuit design techniques, the choice of which largely depends on the operating frequency of the circuit

There is inevitably some overlap of each approach's useful frequency range of application, and the techniques may often be blended together in the same design

· “all-transistor” techniques

· lumped-element techniques

· distributed-element techniques

ALL-TRANSISTOR

LUMPED ELEMENT

MICROSTRIP

0 20 40 60 80 100 GHz

MICROMACHINED STRUCTURES

CPW

Circuit Design Techniques



All-transistor Techniques

· circuits tend to use small device peripheries so that the resulting small input and output capacitances do not unduly affect performance (e.g. operational amplifiers)

· usable up to at least 5 GHz, and such high frequency of operation is achieved largely because of the low capacitance, rather than the use of microwave design techniques

· the design of these circuits at GHz frequencies requires tremendous design skill and experience. This is available in the silicon industry, but generally not in GaAs industry

· the major advantage of active techniques is their high packing density, leading to competitively priced products, but at the expense of increased DC power consumption



'all-transistor' circuit: 2 GHz MMIC band-pass filter (employing 3 active inductors)



'all-transistor' active inductors (equivalent Q-factor of 15,000)



2 GHz MMIC active band-pass filter frequency performance



The advantages of active filters are:1. small size and mass2. low cost in mass production3. high selectivity4. easy integration with amplifiers, mixers, oscillators5. potential for electronic tuning.

Drawbacks associated with active techniques:1. poor noise figure2. non-linearity3. danger of oscillation4. complex bias circuitry and significant DC power5. sensitivity to fabrication tolerances6. environmental sensitivity



Pre-driver and Receiver Applications



SiGe HBT 80 Gb/s Distributed Amplifier, chip size = 1.3 x 1.7 mm2

O. Wohlgemuth et al. (Lucent), EuMC 2003



Lumped-element Techniques

· for higher operating frequencies, the transistor’s input and output capacitances must be accounted for

· lumped-element matching networks (using spiral inductors and overlay capacitors) provide the best solution at frequencies below 20 GHz.

Lumped-element circuit: 1 to 2 GHz MMIC feedback amplifier (employing L-C

components)

VDVG

INPUT

OUTPUT



A spiral transformer Marchand balun (0.7 x 1.5 mm2)

Port 2

Port 1

Port 3



Lumped-distributed equivalent of a quarter-wave transmission line

sin4/Z

Zo 4/

cos

ZC

CC

Z 0 , l



Lumped-distributed branch-line coupler

CC

CC

Input Direct

CoupledIsolated



The lumped element equivalent of a quarter-wave transmission line

L =Z o

w

C C =Z ow1



Lumped-element Wilkinson power divider

C

C

2C

L

L

2ZoIN

OUT

OUT



Lumped-element branch-line coupler

L1

C

C

L1

L2

C

C

L2

Input Direct

CoupledIsolated

radio frequency engineering lecture #1 passives - extra stepan lucyszyn...

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