Oscillator Design with GENESYS - Keysight 10 Optimized Cascade Design Optimized Colpitts transmission and reflection responses OscOut ) C4 LoopIn LoopOut 330nH L1 0.011A CP1 J310 5V

Oscillator Design with Genesys

with techniques from the book

Discrete Oscillator

Design:linear, nonlinear, transient and noise

domains

by Randy Rhea

Slide 2

I'll Cover

• A unified design process for different active devices,

resonators and simulation technologies applicable from low

frequency to microwaves

• How Genesys aids the design process

• What the book offers

• Example Genesys workspaces

Slide 2

Randy Rhea Susina LLC

[email protected] Sept 16, 2010

Slide 3

Step 1

Perform a linear analysis

• This is the design foundation

– determines design margins

– reveals tuning characteristics

– estimates phase noise

– fast exploration of topologies

• Provides intuitive grasp of the design process

• Does not provide level, harmonic or transient data

Slide 3



Slide 4

Two Linear Analysis Methods

• One-Port Reflection

AMPLIFIERRESONATOR

LOOP_INPUT LOOP_OUTPUT

OSCILLATOR_OUTPUT

• Open-Loop Cascade

RESONATOR DEVICE

REFLECTION_PORT OSCILLATOR_OUTPUT



Slide 5

The Open-Loop Cascade

Slide 5

Initial 40 MHz Colpitts with a FET device and an L-C resonator

50ΩOscOut

.01μF

C4

LoopOutLoopIn

270nH

L1

0.011A

CP1

J310

5V

180pF

C3

180Ω

R2

27ΩR1

74.7pF

C1

180pF

C2



Slide 6

Oscillator Starting Conditions

Slide 6



The open-loop response criterion that insure the oscillator will start are

• The oscillation frequency is the transmission phase zero-crossing, f0

• The initial linear gain at f0

must be greater than 0 dB

• The phase slope at f0

must be negative

Additional objectives are

• The phase slope should be as steep as possible

• The maximum phase slope occurs at f0

• The gain margin at f0

is moderate, for example 3 to 8 dB

• The amplifier is stable

• The maximum gain margin occurs at f0

• S11 and S22 are small

Slide 7

Initial Linear Cascade Response

Slide 7

Initial 40 MHz Colpitts transmission and reflection responses

Frequency (MHz)

S21 (

dB

)

0

3

6

9

12

15

18

QL, S

21 a

ng

-90

-60

-30

0

30

60

90

Frequency (MHz)

38 39 40 41 42

S21QLS21 ang

0

0.1

0

.2

0.3

0

.4

0.5

0

.6

0

.7

0.8

0

.9

1.0

1.2

1

.4

1.6

1.8

2.0

3.0

4.0

5.0

1

0

20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 0

.9 1.0

1.2

1.4

1. 6

1. 8

2.0

3.0

4.0

5 .0

10

20

50

0. 2

0.4

0. 6

0.8

1.0

0.2

0.4

0.6

0.8

1.0

0 .1

0.2

0.3

0.4

0.5

0. 6

0.7

0.8

0.9

1.0 1

.2

1.4

1.6

1.8

2.0

3.0

4.0

5.0

10

20

50

0.2

0.4

0.6

0.8

1.0

0.2

0 .4

0.6

0.8

1 .0

S11

S22

40MHz: -12.735dB, -167.772°

40MHz: -0.344dB, 12.728°



Slide 8

Randall/Hock Correction

1212212211

1221

21 SSSSS

SSG

Slide 8

G is the true open-loop complex gain with the loop self-

terminated.

[1] M. Randall and T. Hoch, "General Oscillator Characterization Using Linear Open-

Loop S-Parameters," IEEE Trans. MTT, Vol. 49, June 2001, pp 1094-1100



Slide 9

Optimizing the Open-Loop Response



Slide 10

Optimized Cascade Design

Slide 10

Optimized Colpitts transmission and reflection responses

50ΩOscOut

.01μF

C4

LoopOutLoopIn

330nH

L1

0.011A

CP1

J310

5V

180pF

C3

180Ω

R2

120ΩR1

48pF

C1

390pF

C2

Frequency (MHz)

S21, S

tart

Opt:

S21 (dB

)

0

3

6

9

12

15

18

QL

, S21

ang

, Sta

rtOpt:Q

L, S

tartO

pt:S

21 a

ng-90

-60

-30

0

30

60

90

Frequency (MHz)

38 39 40 41 42

S21QLS21 angStartOpt:S21StartOpt:QLStartOpt:S21 ang

0

0.1

0

.2

0.3

0

.4

0.5

0

.6

0

.7

0.8

0

.9

1.0

1.2

1

.4

1.6

1.8

2.0

3.0

4.0

5.0

1

0

20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 0

.9 1.0

1.2

1.4

1. 6

1. 8

2.0

3.0

4.0

5 .0

10

20

50

0. 2

0.4

0. 6

0.8

1.0

0.2

0.4

0.6

0.8

1.0

0 .1

0.2

0.3

0.4

0.5

0. 6

0.7

0.8

0.9

1.0 1

.2

1.4

1.6

1.8

2.0

3.0

4.0

5.0

10

20

50

0.2

0.4

0.6

0.8

1.0

0.2

0 .4

0.6

0.8

1 .0

S11

S22

StartOpt:S11

StartOpt:S22

40MHz: -12.735dB, -167.772°

40MHz: -0.344dB, 12.728°

40MHz: -17.841dB, 39.881°



Slide 11

Alechno Technique

Slide 11



[1] S. Alechno, "The Virtual Ground in Oscillator Analysis – A Practical Example",

Applied Microwave & Wireless, July 1999, pp.44-53

Slide 12

Back when…….

• A random combination of a device and resonator may not satisfy the starting criterion

• Historically, successful combinations were named for the discoverer and became standards

• Copying designs was (and is!) common, often resulting in nonoptimum performance

• Modern linear, nonlinear and transient simulation is a better method that improves designs

Slide 12



Slide 13

Unified Approach

• These techniques are general

• All resonator or device types are treated in a like manner

• In Genesys, the same schematic is used for linear, nonlinear,

transient and noise simulation

• Ideal or real models are treated in a like manner

Slide 13



Slide 14

Step 2

Perform a harmonic-balance simulation

• This determines the output level and harmonics

• Predicts noise more accurately

• Predicts the frequency more accurately

Requires nonlinear device models

• Numerous models are provided with Genesys

• Genesys imports Spice models

• Devices can also be characterized by

X-parameters

Slide 14



Slide 15

330 MHz Colpitts & Spectrum

Slide 15

330 MHz Colpitts simulated through the 7th harmonic

0.02ACP1

BFT92

Port_2

Port_3

9V

20pFC1

Port_136pFC2

2700Ω

R1

4700Ω

R2

47pFC3

270pF

Csimulation

150ΩR3

FB

27Ω

10pF

C4

120

16.16nHL1

1 2 3

Open_Loop

50Ω

Output1.155V

330.028MHz

OSCPORT

Frequency (MHz)

Po

ut (

dB

m)

-50

-40

-30

-20

-10

0

10

Frequency (MHz)

0 330 660 990 1320 1650 1980 2310

Pout

330.0

28 M

Hz

8.321 dBm

1*330.028



Slide 16

Nonlinear Noise Analysis

Slide 16



Slide 17

Nonlinear Noise Analysis Plot

Slide 17

4 most significant noise contributors of the 330 MHz Colpitts bipolar oscillator

Frequency (MHz)

Q1 B

ase, O

utp

ut Therm

al, Q

1 C

olle

cto

r, F

B (dB

)

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

Frequency (MHz)

100e-6 1e-3 0.01 0.1 1 10 100

Q1 Base

Output Thermal

Q1 Collector

FB



Slide 18

Step 3

Perform a time-step transient analysis

• This determines the starting characteristics

• This helps discover transient spurious modes

• Can be used as a substitute to HB to find output level and harmonics if

nonlinear noise estimates are not required

Uses the same models as HB simulation

Slide 18



1

50Ω

Output

1 2 3

Data_Linear1

Slide 19

Output Waveform

Slide 19

330 MHz Colpitts transient starting waveform

Time (ns)

VP

OR

T (

V)

-2

-1.6

-1.2

-0.8

-0.4

0

0.4

0.8

1.2

1.6

2

Time (ns)

0 20 40 60 80 100 120 140 160 180 200



0.02ACP1

BFT92

Port_2

Port_3

9V

20pFC1

Port_136pFC2

2700Ω

R1

4700Ω

R2

47pFC3

270pF

Csimulation

150ΩR3

FB

27Ω

10pF

C4

120

16.16nHL1

Slide 20

Genesys Oscillator Analysis

Slide 20



Slide 21

Genesys is

• An integrated linear, nonlinear, transient, noise simulation

environment with schematic and layout tools

• A process for creating new oscillator designs or repairing under

performing designs

• A learning tool that provides intuitive insight into all aspects of

oscillator behavior

Slide 21



Slide 22

Oscillator Topics Not Covered in this Webinar

• Genesys oscillator synthesis

• Integrated layout tools

• Electromagnetic simulation of the layout

• Instrument control for data acquisition

• System simulation

Slide 22



Slide 23

Why Did I Write the Book?

• My previous books only covered nonlinear

and transient theory qualitatively

• I gained knowledge while teaching an

oscillator design course to over a thousand

engineers

• Both oscillator and simulation technologies

have advanced significantly in the last decade

• I needed something to do

Slide 23



Slide 24

What's in the Book ?

• Detailed descriptions of linear, nonlinear, transient and noise

techniques for practical oscillator design

• 350 illustrations

• 200 applicable equations

• 60 example oscillators covering bipolar,

FET, and MMIC devices with R-C, L-C,

ceramic, crystal, SAW and distributed

resonators

• Confirmation data for a dozen

prototype oscillators

Slide 24



Slide 25

Genesys Workspaces

140 Genesys workspaces were used to create the illustrations in the book. Genesys is a powerful documentation tool.

• Agilent EEsof EDA has established a website for downloading 73 of the more important workspaces

• These workspaces may be used with either full or trial Genesys licenses

Slide 25



Slide 26

The Available Workspaces

• The workspace template.wsx may be used to start a design. Simply add your schematic to the workspace

• There are 13 utility and tutorial workspaces for amplifier and resonator design

• There are 27 workspaces for general purpose oscillators

• There are 13 workspaces of VCOs and distributed resonator oscillators

• There are 20 workspaces with ceramic, crystal and SAW oscillators

Slide 26



Slide 27

Summary

• Genesys is an integrated tool, ideally suited for a unified

approach to oscillator design

• Discrete Oscillator Design covers practical oscillator design for

a wide variety of oscillator types

• Example Genesys workspaces from the book are available

from Agilent EEsof

Slide 27



Slide 28

For More Info: Just Google “Agilent Genesys”

Email Randy Rhea at [email protected]

• for questions about this presentation• for questions about the book• for a Microsoft Excel spreadsheet of equations in the book• for an errata sheet for the book, as published

About Genesys:• Genesys product page http://www.agilent.com/find/eesof-genesys• USA Genesys Specialist, Rick Carter [email protected]

To download the workspaces:• Go to http://www.agilent.com/find/eesof-genesys-osc-workspaces

To obtain a free trial Genesys license:• Go to http://www.agilent.com/find/eesof-genesys-evaluation

Slide 28



Documents

Oscillator Design with GENESYS - Keysight 10 Optimized Cascade Design Optimized Colpitts transmission and reflection responses OscOut ) C4 LoopIn LoopOut 330nH L1 0.011A CP1 J310 5V