rf circuit synthesis for physical wireless design · • start with filter type shape –low-pass,...

RF Circuit Synthesis for

Physical Wireless

Design

Overview

Subjects

• Review Of Common Design Tasks

• Break Down And Dissect Design Task

• Review Non-Synthesis Methods

• Show A Better Way To Solve Complex Design Challenges

Audience

• Designers Tasked With Rapid Development Of System Components

RF Wireless Community

CABLE

CELLULAR

RFID

GOVERMENT

INSTRUMENTS

SATELLITE

WIFI

NAVIGATION

COMM DEVICES

Wireless Devices

System Architecture

Starting from a system level view

• Assemblies of component units constitute a system

– The component parameters are generated by system requirements

– Made up of one or more…

• Amplifier

• Mixer

• Filters: Microwave and Passive Lumped

• Couplers/splitters

• Oscillators etc.

– We start by breaking down tasks to individual modules

• Design of one or more require unique skills

Today’s Focus is on Four Design Tasks

• Microwave Filter Design

• Lumped Passive Filter Design

• Signal Control Elements

• Matching for Optimum Power Transfer

Component Design Tasks

The Non-Synthesis Method

• Experience is required to choose topology, equivalent circuits and strategy for failed performance

• Links to physical realization is a manual process

– Conversion to micro-strip, slab-line, strip-line etc.

• Does not guarantee optimum design

– Best performance, Component count, Size, Materials

• Matching tools are limited i.e. Smith chart

• Time and Resource Consuming

– Hours, days, or even weeks to complete

– Missed deadlines

– Board Turns

Non Synthesis Techniques

To Manufacture

Select Topology

And

Components

Optimize

Response

Met Goals

Convert To

Physical Format

YES

NO

Build Device

Test Device

EM

Solver?

YES

NO

Met Goals

Met Goals

YES

NO

NO

YES

Strategy?

Strategy?

Microwave Filter Design Task

2.4 GHz WiFi Front End Microwave Filter

• System Specifications / Goals

– Frequency- 2350-2550 MHz

– Insertion Loss- -2dB

– Shape- Butterworth

– Order- 3


MFILTER- A Better Way

• Start With Filter Type Shape

– Low-pass, High-pass, Band-pass, Band-reject

• Shape

– Butterworth, Chebyshev, Bessel etc.

• Subtype

– Eight physical formats


Which topology is best?

• Distributed Filters Exhibit Recurring Band Pass

– Where and how many is a function of filter type

– COMB filters have control over the band where

response is repeated

• Filter Size varies

• Cost-COMB requires a capacitor for each resonator

We have selected a Hairpin Design for this demonstration


Settings

• Select Z0, Order, Start-Stop frequencies

• Select Resonator Zo

• Select Tapped / Coupled


Advanced-TLINE automatically converts to a physical form including discontinuities, bends, chamfers, and steps


Synthesized Hairpin Filter

Hairpin Filter with Modeled Microstrip Loss and Dispersion

Advanced TLINE


Using Built-in Optimizer

• Fine tune for the discontinuities, bends, loss, dispersion effects etc.


Using Monte Carlo Determine

• Effect of Loss Tan

• Effect of etching tolerance e.g. spacing

• Effect of Er


•Layout Filter

•Perform EM Simulation

•Export To Manufacturer

•Test Completed Filter


• Measure Filter

– TESTLINK

• Compare to Simulation

Measured

EM

Modeled


Performance Summary

Center Frequency 2450 MHz 2390 MHz

Bandwidth 200 MHz 260 MHz

Insertion Loss 2 dB 3.2 dB

$ Cost ? ~$0.50

Note: Know your substrate material especially ER and Loss Tan


Link data to SPECTRASYS’ behavioral model

Po=1.2 dB

NF=0.1dB


MFILTER- A better way

• Classical synthesis shapes

– Butterworth, Chebyshev, Elliptical etc.

• Multiple topologies

• Instant schematic and graphical updates

• Coupled or Tapped input

• Multiple physical realizations e.g. stripline, microstrip, inverted microstrip etc. via Advanced T-Line

– Automatic compensation of vias, grounds, steps, and T-Junctions

• Direct link to layout and EM simulation engine

• Monte Carlo, Yield and what If analysis

• Measurement of Device via TESTLINK

Lumped Filter Design Task

70 MHz IF Filter

• System Specifications / Goals

– Frequency- 60-80 MHz

– Insertion Loss- 0.5dB ?

– Shape- Butterworth

– Order- 14 ?


PASSIVE FILTER - A Better Way

• Start With Filter Type Shape

– Low-pass, High-pass, Band-pass, Band-reject

• Shape

– Butterworth, Chebyshev, Bessel, Elliptical etc.

• Subtype

– Eight physical formats

• Some Formats Lend Themselves Better to Wide or Narrow Responses

Note: Changes in schematic and graph when parameters are changed is Instantaneous

Which Shape And Subtype To Pick?

• Component Count

• Response BW, Group Delay

• Out Of Band Response

– Symmetry, Roll Off

• Ease of Manufacture

– Common Inductance or Capacitance

Balanced Circuit at a Buttons Click!


Multiple Filter Shapes

• Butterworth

• Chebyshev

• Bessel

• Singly Terminated

– For Diplexers etc.


Settings

• Input / Output Resistance

– Not limited to 50 ohms or symmetrical impedances!

• Cutoff Frequencies

• Filter Order

• Specify Cutoff Attenuation

• Common L or C for some filter types



Response of Synthesized Shunt C Coupled Filter

• Shunt C Coupled filter results in common inductor

– Five Sections Chosen


Using Standard Values Results in Shifted Response

• Tune Standard Values for best results

Original vs. standard values


Replacing Ideal Std Values with Manufacturers S-data

• Increased insertion loss due to finite Q’s of components

• Be Mindful of SRF and Qs of Manufacturer’s Components and The Frequency range of their data

Original vs. S-data values


Perform Layout and EM Simulation


EM simulation with S-Data Parts

Use Co-Simulation to Fine Tune Standard Valued S-Data

• Only a single EM simulation is required

since copper pattern is invariant

Filter with S-data specified parts

EM Filter with S-data specified parts


Comparison of Original Synthesized Filter

Use Monte Carlo for Yield and Manufacturability


Pad and Dielectric Effects

• More prominent at higher frequencies, 500MHz Filter example shown

Er= 3.9, 4.5, 4.9

H=10mil

H=30mil

H=59mil


Pad and Dielectric Effects

• More prominent at higher frequencies

• Co-Simulation feature is used to re-tune filter

EM std values

L=39

Ca=5.6

Cb=3.9

Cc=18

Ccd=3.6

EM std values otpz

L=39

Ca=3.3

Cb=2.4

Cc=7.5

Ccd=2.4

EM results in shift due to pad effects Std value tuning brings filter back


Performance Summary

Center Frequency 70 MHz

68.1 Std Pts

67 MHz

Bandwidth 20 MHz

17.3 Std Pts

17 MHz

Sections 14 5

Insertion Loss 0.5 dB 3.9 dB

$ Cost ? ~$2.90 (16x$0.15)

Note: Know your substrate material especially ER and LossTan


Link data to SPECTRASYS’ behavioral model

• When S-Parameter File is Substituted For Behavioral Model In System Simulator

– Note: 3db Additional Loss And Increase In Spur Level (below noise floor) And An

Increase Of 0.11dB In Noise Figure


PASSIVE FILTER- A better way

• Classical synthesis shapes

– Butterworth, Chebyshev, Bessel, Singly Terminated etc.

• Multiple topologies


• Single or Balance types


– Co-Simulation aides final optimization

• Monte Carlo and Yield analysis


Signal Control Design Task

What is Signal Control?

• Distribution And Control Of Power Through The Use Of

– Couplers, Splitters, Dividers, Attenuators, Baluns

• Where Is It Used?

– Power Monitoring, Amplifiers, Mixers, Power Combining, Beam Forming


Signal Control Elements

• Splitters

– Single or Multi-section, 0 deg, 180 deg

• Couplers

– Lange, Backward Wave, Lumped

• Power Dividers

– Distributed, Lumped

• Balun

• Attenuators


SIGNAL CONTROL, a better way!

• Topology

– Selection of over 43 topologies

• Splitters

• Couplers

• Power Dividers

• Baluns

• Attenuators


Settings

• Selection of:

– Impedance

– Coupling Factor

– Upper/Lower cutoff

– Number of Sections

– Number of Outputs

– Optimization Goals

– I/O line lengths


Instant Realization

• Dynamic Schematic and Graphs


Options

• Create a Layout

• Use Advanced TLINE to Convert to Physical Format


Options

• Manufacturing Process

– Select Physical Form

• Switch between any of the

processes (e.g. ideal to

microstrip, stripline to microstrip

etc.)

– Accounts for discontinuities,

corners, steps etc.

– Uses selectable substrate

definition


Conversion to Microstrip Causes Shift

• Shift due to non-ideal models, losses, dispersion etc.

– Re-optimize element parameters to specifications

Shift due to Microstrip


Layout Is Created By Checking Box in Options Tab

EM Simulation Is Performed To Verify Design Goals


EM Simulation Shows Difference In Isolation Between Output Ports

EMPOWER’s Ability To Co-Simulate Allows The Tuning Of Isolation

Resistor For Optimum Isolation

Optimum R= 91 ohms instead of 100 ohms


SIGNAL CONTROL- A better way

• Over 43 Topologies

– Splitters, Couplers, Baluns, Attenuators

• 0 deg, 90 deg, 180 deg types

– Multiple outputs, Multiple stages


• Optimization of final process





• Link data to SPECTRASYS’ behavioral model

Matching Design Task

Where is Matching used?

• At Almost Every Interface Between Connected Components

– Minimize Power Loss Between Entities


Front End Receiver Amp Parameters

• Frequency Range 2200 MHz to 2600 MHz

• Gain 30dB

• Noise Figure 3dB

• Match Nominal 50 Ohm Input/Output

• P1dB +10dBm

• PSAT 13dBm

• TOI 20dBm


Complex Matching Issues

• Simultaneous Matching For Noise Figure, Input/Output, and Interstage

– Difficult Using Manual Techniques, Especially For Conditionally Stable Device

Selected Part Meets Our Gain And Noise Figure Needs

NE52418


Conditionally Stable

• Simultaneous Input/Output Match Is Not Possible

• Good News, Noise Figure Meets Our Goal With 50 Ohm Input


MATCH A Better Way

• Ideal For Complex Multistage

Matching

• Real Or Complex Terminations

– File Based Complex Data For

Terminations / Devices

• Multitude Of Available Matching

Structures

– Lumped And Or Distributed


Nominal Goals Met With Interstage Matching Sections


Matching Network Incorporated Into Design

• Use Advance TLINE

– Converts To Physical Process

• Includes Steps, Discontinuities, Vias, etc.


Monte Carlo Analysis

•Matching <100% Yield, Determine Effect On System Or End User

•Gain And NF 100% Yield


Optimize Circuit For Response And Match

•Measure Pertinent Parameters

– Frequency Range 2.2 GHz-2.6 GHz

Gain 30dB +/- .5 dB

Noise Figure 1.06 dB

Match <-15dB

? P1dB 0 dBm (10 dBm)

? TOI 18.6 dBm (20 dBm)

? PSAT 10.4 dBm (13 dBm)


Replacing Behavioral Model With Design

•No Significant Change In Spur Or Harmonic Content

•Noise Figure Improved by 2dB


MATCH- A better way

• Multiple matching networks and topologies

– Mix and match between distributed and lumped networks

• Match to real, complex and S/Y/Z files

– Broadband matching, Multi-stage matching





• Link Data To SPECTRASYS’ Behavioral Model

Summary

Reviewed Of Common Design Tasks

Reviewed Non-Synthesis Methods

Showed A Better Way To Solve Complex Design Challenges

• Synthesis

• Incorporating Standard Values

– Substituted Measured S-Data For Accuracy

– Optimized Performance

• Layout And EM Simulation For Verification

• Exported Data For Incorporation Into Higher Level Design

We Showed A Comprehensive Set Of Tools, In a Common Environment For Rapid Development, Improving Time To Market With Fewer Re-Designs

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rf circuit synthesis for physical wireless design · • start with filter type shape –low-pass,...

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