Lesson 1: Introduction

Welcome to this course on mixed-signal hardware design!

In this lesson, I'll tell you more about this course, the pre-requisites, what you will learn in this course, and how the course is structured.

Lesson length: 00:05:23

Lesson 2: System Requirements

Starting from a very basic system description, we will go through - step-by-step - and define our system requirements. Initially, we'll start with a broad overview of what our product needs to be capable of, then gradually 'hone' in on far more detailed system requirements.

Lesson Sections:

• Basic System Description
  We'll get given a very basic product brief, defining what our system should be capable of.
• Defining Basic System Requirements
  Given the product brief, we will define a number of basic system requirements.
• Refining System Requirements
  Once we have basic system requirements in place, we can hone in and refine our system requirements adding more and more detail along the way. Following that, we'll look at individual, sub-system requirements.
• USB Requirements
  Power, data rates, connector type, version/protocol, 'Host, Device, or OTG'.
• Processor Requirements
  Storage capabilities (flash/RAM), programming tools, peripherals, processing power, packaging, brand?
• Power Supply Requirements
  Linear or Switching, current-/power-handling requirements, filtering, input and output voltages, USB capabilities.
• Data Converter Requirements
  ADCs and DACs, number of channels, number of bits, sampling rate, additional features, interface (SPI, parallel, ...).
• Analogue
  Anti-aliasing/reconstruction filters, buffers, impedances, single-ended/differential.
• Miscellaneous
  Mechanical constraints, connectors, peripherals, ESD protection, EMC, biasing, timing.
• System Block Diagram
  Given our more detailed system requirements and system description, we can create an initial block diagram.

Lesson length: 00:20:38

Lesson 3: Part Selection

How to choose suitable parts (ICs, passives, ...) for our specific design, given our derived system requirements.

Lesson Sections:

• Part Selection Basics
  Which parts to choose first, calculating power requirements, choosing additional components (passives), choosing connectors.
• Finding Suitable Parts
  How to find suitable parts (stock, PCB assembler, familiarity with parts, distributor part search).
• Distributor Part Search
  Example demonstration of Mouser's part search to find a suitable microcontroller.
• Microcontroller Selection
  Important microcontroller (MCU) parameters: speeds, flash and RAM sizes, peripherals, brands, packages, ....
• ADC and DAC Selection
  Important data converter parameters, part choices given our requirements.
• DC/DC Converter Selection
  Supply requirements leading to converter selection, LDO for analogue, switching (buck) for digital, specific part choices and reasons for choosing them, preview of required surrounding circuitry.
• Analogue Component Selection
  Low-noise design principles (resistor Johnson noise), op-amp selection (input type, rail-to-rail, bandwidth, etc.), ADC and DAC interfaces, filters.
• Additional Component Selection
  Voltage/current/power ratings, material/process types, temperature coefficients and tolerances, package sizes, ESD protection and EMI filters.
• Final Points
  BOM consolidation, standard value compoennts, easy-to-assemble/debug packages.

Lesson length: 00:24:20

Lesson 4: How To Read A Datasheet and Circuit Design Introduction

How to read a datasheet (typical and useful sections) and introduction to the next part of the course: circuit design.

Lesson Sections:

• Datasheet Overview and Table of Contents
  Standard layout of a datasheet, and typically most useful sections,
• Pin Configuration and Functions Section
  Pinout of specific device, useful for schematic symbol creation.
• Ratings and Operating Conditions Section
  Absolute maximum ratings, recommended operating conditions, incorporated ESD protection.
• Application and Implementation Section
  Example schematic, component values and sizing for required external circuitry
• Layout Guidelines Section
  Important information for laying out and routing the specific part.
• Package and Footprint Section
  Package/footprint information to aid the design of a suitable component footprint in our ECAD software.
• Circuit Design Introduction
  Moving to KiCad to examine schematic in next lesson, looking at following sections: power supplies, microcontroller and USB, ADC and analogue circuitry, DAC and analogue circuitry.

Lesson length: 00:05:43

Lesson 5: Schematic Design - Power Supply

Starting with circuit design and analysis, we'll move over to KiCad and examine the schematic in sections of our mixed-signal demo hardware. In this first schematic lesson, we'll look at some basic schematic tips for readability and sectioning, as well as the entire power supply circuitry for our prototype product.

Lesson Sections:

• Schematic Overview and Tips
  How to section a schematic, tips and tricks for readability, and a brief overview of our entire schematic in KiCad.
• Power Supply Overview
  Input filter, analogue supply, digital supply, and op-amp bias generator.
• Input Filter and RLC Filters
  Filtering noisy USB power rails, RLC filter theory, choosing suitable component values, RLC filter design using online tools.
• Analogue Supply
  Linear, low drop-out (LDO) regulators and surrounding circuitry.
• RC Filters
  RC filter theory and design, analogue supply filtering, power dissipation in resistors.
• Labelling Nets
  Incredibly important design step: label ALL nets.
• Digital Supply
  Switching, buck converter for digital circuitry supply rail. Buck convert component selection and sizing (inductor, capacitors, feedback network).
• LEDs and Current-Limiting Resistors
  Extracting relevant information from LED datasheet, typical current requirements and forward voltages, calculating suitable current-limiting resistor values to adjust LED brightness.
• Bias Generator
  Configuring an op-amp as a voltage follower to generate a stable bias voltage for op-amps in the analogue front-ends. Supply filtering and reference generation.
• Decoupling/Bypass Capacitors
  Decoupling capacitor theory, reasons for requiring decoupling capacitors, rough sizing and placement guidelines.

Lesson length: 00:31:36

Lesson 6: Schematic Design - Microcontroller, USB, SWD, and ESD Protection

Moving on to the next schematic page, containing the microcontroller (STM32), programming interface (SWD), and USB circuitry. We'll also examine circuit protection features, such as current-limiting resistors and ESD protection.

Lesson Sections:

• Overview
  Overview and sectioning of schematic page into logical groups.
• Microcontroller Circuitry
  Decoupling capacitors, VDDA filtering, configuration pins, crystal oscillator connections.
• Crystal Oscillator Circuitry
  Crystal oscillator component selection and sizing, load capacitors and feed resistor calculations.
• Pin-Out Planning
  Initial pin-out, including peripheral selection (SPI, USB, SWD, Timers, ...) for STM32 microcontroller using STM32CubeIDE.
• Pull-Up Resistors
  Required pull-up resistors on certain datalines, app notes that detail requirements.
• RGB LED
  Current-limiting resistors for RGB LED, decoupling, connection to timer channels for PWM duty-cycle-based control via MCU.
• USB
  Type C connector specifics, CC resistors for power delivery, ESD protection, and filtering using common-mode chokes.
• Serial Wire Debug
  SWD header pinout, protection circuitry with current-limiting resistors and ESD protection, adding capacitance to NRST line.
• TVS Diodes
  How to quickly choose the right TVS diode for ESD protection, depending on voltage requirements and bus speeds.

Lesson length: 00:31:39

Lesson 7: Schematic Design - ADC, DAC, and Analogue Circuitry

In this lesson, we'll examine the final two schematic pages - those of the ADC and DAC, as well as all corresponding analogue circuitry ('front-ends').

Lesson Sections:

• ADC Datasheet
  Overview of ADC, including features, and pin-out.
• Symbol Creation
  How to create a custom symbol in KiCad 6 using the datasheet as a reference, including proper sectioning of symobls (digital, analog, ground, and power).
• ADC Surrounding Circuitry
  Using the datasheet to add the required external circuitry to the ADC, such as decoupling capacitors.
• Voltage Reference
  Using an additional IC voltage reference to feed the ADC, voltage reference filtering and bypassing.
• Analogue Front-End
  BNC input connector, ESD protection, RF filter, AC coupling, biasing, op-amp buffer with defined input impedance, analogue anti-aliasing filter design (3rd order Butterworth, Sallen-Key), single-ended to 'pseudo'differential/balanced conversion.
• DAC and Analogue 'Rear-End'
  Required surrounding circuitry for DAC, analogue reconstruction filter, output buffer, ESD protection, and BNC connector.

Lesson length: 00:23:23

Lesson 8: Final Schematic Tips, Footprint Selection, and Footprint Creation

Final steps when creating the schematic, as well as selecting and creating custom footprints in KiCad.

Lesson Sections:

• Annotation
  How to logically annotate multi-page schematics.
• Electrical Rules Check
  Performing an ERC to catch any schematic capture mistakes.
• Footprint Selection
  Guidelines to help choose suitable footprints, for example, passive sizes depending on requirements.
• Footprint Creation
  Using the ADC datasheet to create a custom footprint in KiCad.
• 3D Models
  Retrieving a 3D model, and adding it to our footprint.

Lesson length: 00:08:56

Lesson 9: Circuit Simulation with LTSpice

After creating our initial schematics, we can simulate parts of our circuitry using free tools. We will use LTSpice to simulate a simple op-amp bias generator, both with a DC operating point and AC frequency response analysis.

Lesson Sections:

• LTSpice Overview
  Placing components, voltage sources, net names, and navigating around the LTSpice GUI.
• DC Operating Point Anaylsis
  Steady-state, DC analysis of an op-amp bias generator to check DC node voltages and currents.
• AC Frequency Response Analysis
  Simulating and analysing the frequency response of an RC, low-pass filter across a defined frequency band.

Lesson length: 00:09:35

Lesson 10: PCB Design - Introduction

Once we have our schematic and footprints in place, we can move over to PCB design. We'll start off our design with a discussion about some PCB design basics and guidelines.

Lesson Sections:

• Checking Your Work
  Before continuing, make sure to thoroughly check schematics, symbols, datasheets, footprints, and simulations.
• Recommended Resources
  Several recommended (free) videos to cover PCB design basics.
• PCB Stack-Up
  Looking at general PCB stack-ups, comparing two four-layer PCB stackups, and benefits and drawbacks of each.
• The Signal Path
  Discussing how electrical signals flow through a PCB and how this influences our decision of which stack-up to use.
• Traces
  Guidelines for trace thickness, width, spacing, depending on power or signalling requirements, example current-handling capability calculations in KiCad.
• Controlled Impedance Traces
  Brief overview of controlled impedance traces, why they are necessary, and using various methods to calculate required trace widths - depending on stack-up - to control impedance.
• Vias and Through-Holes
  Determining via properties, pad width, drill sizes, and annular rings, recommended sizing, and guidelines.

Lesson length: 00:21:15

Lesson 11: PCB - Design Rules and Set-Up

Before we can begin with our rough board layout and component placement, we need to set up our PCB in KiCad, as well as to import design rules from our chosen PCB manufacturer.

Lesson Sections:

• Board Set-Up
  Defining board in KiCad, layer count, stack-up, signal and power layers, and surface treatment.
• Design Rules
  Walking through design rules available in KiCad, looking at typical PCB manufacturer capabilities, figuring out design rules from capabilities, importing design rules into KiCad.
• Track and Via Dimensions
  Adding standard track and via dimensions to our predefined settings in KiCad, importing controlled impedance calculations.
• Miscellaneous Set-Up
  Brief look at KiCad's default custom net class editor, custom rules editor, and violation severity settings.

Lesson length: 00:08:02

Lesson 12: PCB - Layout

We are now ready to begin with the layout of our PCB. Beginning with a very rough placement of the circuitry, we'll hone into the final layout, section-by-section and step-by-step. Throughout, we'll be discussing tips and tricks for properly laying out mixed-signal PCBs that'll make our routing life easier afterwards.

Lesson Sections:

• Importing Footprints
  Importing the data from our schematics and placing footprints on the blank PCB.
• Adding Missing 3D Models
  Sometimes links are broken between footprints and their 3D models. Here's how to fix that!
• Microcontroller
  Laying out the microcontroller, decoupling capacitors and their best placement, surrounding circuitry.
• Crystal
  Recommended distance and placement to MCU, correct load capacitor and feed resistor placement.
• Pull-Up Resistors
  Determining priority of components, placing components in the signal path to avoid stubs.
• Serial Wire Debug
  Determining best placement of connector, ESD protection, and current-limiting resistors w.r.t. the microcontroller.
• USB
  Connector, ESD protection, filtering and pull-up resistor placement. Which signal order to place components in, preparing for differential routing later on.
• ADC, DAC, and Analogue Circuitry
  Creating a boundary between digital and analogue sections, sectioning circuitry, component placement for lowest cross-talk, coupling, and noise, filter placement, and analogue circuitry layout.
• Power Supplies
  LDO regulator layout with bypass capacitor and filtering resistor, switching regulator layout with best practices, proper placement of analogue and digital supplies.
• Fine-Tuning Layout and Improving Placement
  Starting with 'islands' of components and component groupings, improving the layout step-by-step, and adjusting connector positions.
• Mechanical
  Determining a board layout after initial component placement, rounding PCB corners, adding standardises mounting holes to the design.

Lesson length: 01:03:40

Lesson 13: PCB - Routing

Having created an initial layout, we are ready to route our PCB. In this lesson, you'll learn best practices and guidelines for mixed-signal PCB routing, as we route all sections of this board together.

Lesson Sections:

• Layer Designation
  Routing layers, ground plane layers, adding ground planes, hiding/showing layers in KiCad.
• Routing Guidelines
  Controlled impedance routing, spacing, trace width, via placement, grounding, decoupling capacitors, etc. - all to minimise noise, cross-talk, EMI.
• Tips and Tricks
  Power puddles and how to best link several, adjacent pads of the same net, ground return path vias for field control, improving routing by changing microcontroller pin-out.
• Digital
  Controlled impedance, differential USB routing, SPI, crystal.
• Analogue
  Routing to minimise interference from digital section, analogue routing guidelines.
• Power Supplies
  Best practices for routing LDO regulators and switching converters. Routing of power traces on signal layers.

Lesson length: 00:49:09

Lesson 14: PCB - Finishing Touches

We need to add some finishing touches to our PCB, including stitching vias and silkscreen.

Lesson Sections:

• Via Stitching
  Reasons for stitching vias, how to place stitching vias.
• Silkscreen
  Labelling connectors and pins, indicating component orientations, adding a custom logo.

Lesson length: 00:04:46

Lesson 15: Getting The Product Manufactured

Once we've cleaned up our PCB and added finishing touches, we can prepare the necessary files to order our boards at a PCB manufacturer with assembly.

Lesson Sections:

• Preparation
  Checking design files, minimum production files required.
• Production Files
  How to export Gerber and drill files, and how to use KiCad's Gerber viewer to check them.
• Assembly Files
  How to export the footprint position file (CPL), and bill of materials file (BOM), including how to edit the export scripts in KiCad, and add manufacturer names, and manufacturer part numbers.
• Example PCB Manufacturers
  Brief look at two PCB manufacturers that offer PCB assembly, checking out the rough ordering process, and how to provide the files.

Lesson length: 00:09:51

Lesson 16: Outro

Congratulations on reaching the end of this mixed-signal hardware design course!

In this final video, I'll show you how to contact me regarding course questions, as well as links to the Phil's Lab YouTube channel and website for more educational engineering content.

Lesson length: 00:01:51