As a young boy, I dreamed about growing up to be an engineer. I dressed up as an engineer and played games that featured me as an engineer with imaginary friends and tasks. My parents satisfied my yearning to become an engineer by buying toys and toy accessories. I spent endless fun hours in an imaginary world pretending to work as a chief engineer.
Looking back, I wonder why I never attained my life-long goal of driving a train. After all, operating a 200-ton, 6,000 horsepower locomotive that pulls 40 loaded freight cars while waving at farmers and kids still seems fun. I still have my blue and white striped engineer’s cap, my railroad lantern, and my O-gauge train sets. Maybe someday I’ll have to work on a career shift...
Analog, RF, and Circuit Behaviors for Analog Design Engineers
Analog design engineers require a significantly different skill set than train engineers. While you mentally digest that extraordinary piece of information, let’s take a look at the primary skills needed to succeed as an analog design engineer.
In a nutshell, analog design, consistency, and problem-solving go hand-in-hand. For example, the precise reproduction, amplification, and filtering of signals requires knowledge of different characteristics that can impact the behavior of an RF circuit. Those characteristics include temperature, supply voltages, and performance specifications. Having that knowledge--and the almost intuitive feel for how a component or circuit should behave--leads to problem solving.
Mixed Signal Behaviors for Analog Design Engineers
Despite having the term “analog” in the position title, analog design engineers need a firm grasp on both analog and digital components and circuit behaviors. For example, the functionality of an analog RF signal circuit depends on speed, accuracy, reliability, cost in the same way as a digital circuit. However, the fundamental differences between analog and digital circuit operation add complexity to analog circuit design. The contrast becomes apparent when looking at inputs and outputs.
Utilizing analog and digital signal knowledge in circuit design will be paramount.
Digital circuits operate with signals either in the off-state or the on-state. All the inputs and outputs are discrete. With analog circuits, though, the inputs and outputs vary as continuous values between a low and a high potential. Because those values constantly change, analog design must consider a broader set of factors than digital-analog engineers.
Along with speed, accuracy, reliability, and cost, analog design must also consider noise, sensitivity, gain, and bandwidth. Rather than considering only inputs and outputs, analog design engineers work to optimize those functions.
Component Noise and Circuit Performance
Problem-solving can overcome challenges because of the impact of noise and parasitic effects on components. Although noise can harm performance and create inefficiencies throughout a circuit, good analog design does not cross the line into over-design and higher costs. For example, analog design engineers know how to use resistance values to increase noise performance and how to use simulation software to perform comprehensive noise calculations.
Using the software allows engineers to simplify noise calculations into the noise equivalent bandwidth (NEB) and to adjust bandwidth accordingly. In addition, analog design discerns when to consider smaller noise sources as part of a larger problem and how to balance the amount of gain in the first stage to achieve better noise performance while not sacrificing sensitivity and range.
An analog design engineer’s mix of knowledge and intuition also assists with selecting components that match circuit requirements. For example, selecting the best op-amp for a circuit can involve specifying both the voltage noise and the current noise so that the combination of current flowing to a voltage through source resistance does not add to existing voltage noise and create larger noise problems for the system.
Working through your design, especially for multilayer designs and signal layers, can prove difficult without proper noise calculations.
Knowledge and intuition may also solidify the selection of analog-to-digital converters (ADC) that do not contribute ADC driver noise to a circuit. Rather than solely following manufacturers’ recommendations, intuition and knowledge may determine that matching ADC noise performance with the desired total noise level for the entire system will yield better system performance.
Pitch Nine Simulated Perfect Innings in a Simulated Game
An analog design engineer uses electronic design automation (EDA) software to visualize and manipulate circuits and components. Then, the design-test-retest process moves to create system designs based on the behavioral relationships between components.
Although often used to set parameters for digital design, EDA software also allows analog design engineers to test how components function within circuits and to determine the best location for amplifiers, filters, and resistors. EDA software also provides methods for setting design rules and establishing tests that disclose whether a circuit functions within those rules.
For EDA software that will best fit your electronic production team necessities, consider the suite of design and analysis tools out of Cadence. Starting with the supreme schematic and layout prowess of OrCAD PCB Designer, you’ll be sure to find anything you need for your circuit expectations.
If you’re looking to learn more about how Cadence has the solution for you, talk to our team of experts and us