Hardware System Validation Test
Introduction:
Consumer electronics have become an integral part of our daily lives, from smartphones and laptops to smart home devices and wearables. As consumers, we expect these products to be not only feature-rich but also reliable and long-lasting. To meet these expectations, manufacturers perform rigorous validation tests on their products' electrical designs. This primer aims to provide a comprehensive overview of essential validation test areas to ensure the performance and reliability of consumer electronics.
Functional Tests:
This is the first tests to ensure hardware readiness before anything else. Functional tests validate all basic functionality for each subsystem of the consumer electronics product. These tests ensure that all components are working as intended and include:
Display functionality: Verify if the display turns on and functions properly.
Sensor functionality: Ensure correct sensor reading (simple check is to write to a register value and read it back)
Voltage regulator output: Ensure the voltage regulator outputs the correct level.
Audio functionality: Check if the audio speaker can be driven effectively.
Radio functionality: Verify proper operation of wireless radios, such as Wi-Fi or Bluetooth.
RF Testing:
RF (Radio Frequency) validation tests focus on verifying the transmitter and receiver performance of wireless devices. The key concepts include the Link Budget and Link Margin.
Link Budget: Accounts for RF path gains (e.g., power amplifier output, antenna gain) and transmission losses (e.g., PCB loss, matching network loss, free space path loss).
Link Margin: Represents the safety margin of the communication link, which is the difference between the received RF signal power at the RF receiver and the RF receiver sensitivity.
Three main RF tests are performed:
Antenna Tests:
Return loss: Evaluates the antenna's ability to reflect transmitted signals back to the transmitter.
Isolation (if multiple antennas used): Checks for interference between multiple antennas.
Efficiency: Measures the antenna's effectiveness in converting RF power into radiated energy.
Radiation pattern: Examines the directionality and coverage of the radiated RF energy in all three planes (XY, XZ, and YZ).
Conducted Test:
Measures the RF transceiver performance without the antenna.
Transmitter path tests: Analyzes average power, peak power, error vector magnitude (EVM), spectrum mask, and frequency error.
Receiver path tests: Validates packet error rate and receiver sensitivity against wireless module specifications.
Radiated Test:
TIS (Total Isotropic Sensitivity): Quantifies the receiver's 3D spatial performance.
TRP (Total Radiated Power): Measures the transmitter's 3D spatial performance.
Rate vs Range Throughput Test:
Assesses downstream and upstream throughput between the device and access point at various simulated distances.
Downstream test: Evaluates the device's downlink receive path quality, crucial for high-quality data streaming.
Upstream test: Analyzes the device's uplink transmit path quality for data transmission.
Signal Integrity Testing:
Signal integrity testing validates the communication timing, voltage levels, and clock stability of digital interfaces. Important tests include:
Signal Eye Diagrams: Provides a visual representation of signal quality.
Clock Jitter: Measures clock stability and noise.
Voltage Levels: Analyzes differential voltage swings and over shoots and under shoots on fast rising edges.
Timing tests: Verify skews for differential pairs, setup and hold time, and rise/fall time.
Signal Trace Impedance TDR Measurements: Ensures impedance compliance for signal traces in single-ended and differential signaling.
Clocks Testing:
Clocks play a critical role in the operation of consumer electronics, providing accurate synchronization for all subsystems. Key clock tests include:
Clock Frequency: Measure to ensure it aligns with the specified value.
Offset and Drift: Check for any deviations from the required timing accuracy over time.
Jitter: Assess clock stability and noise.
Clocks Impact: Incorrect frequency for RF modulators may generate incorrect carrier frequencies, leading to missed target link channel frequencies.
Power Regulator Testing:
Power regulators must maintain voltage regulation under varying load conditions. Tests include:
Line and Load Regulation Test: Evaluates regulation with different input voltage and output current sweeps.
Line and Load Step Test: Assesses regulation during different line input voltage and output load current step sizes.
Voltage Ripple Test: Measures voltage stability.
Efficiency Test: Calculates power efficiency.
Power Distribution Network (PDN) Testing:
PDN validation is essential for high-speed and high-power electronics. Tests include:
Verifying impedance vs. frequency curves for required PDN power pins for both AC and DC power delivery critical paths.
Ensuring effective delivery of charges to high-speed/power loads such as processors and power amplifiers.
Electrostatic Discharge (ESD) Testing:
ESD tests protect electronics from transient voltage that can damage components.
Contact Discharge: Simulates discharge from a human body.
Air Discharge: Simulates discharge in the air.
Measurement:
Use high-bandwidth probes for precise signal integrity measurements.
Minimize ground loops for accurate power measurements.
Summary & Conclusion
In this article, we outlined some common test areas, RF, signal integrity, power regulators, PDN, and ESD. Performing these tests ensure a good quality of design. In the case of shipping products in tens of millions rnage, any small issue is amplified to a significant problem. interesting enough, with high enough volume, new problems arises,
As a good designer, we must come up with a validation test plan early and start testing as soon as possible, and make changes accordingly. Hardware development is a game of racing against a fixed schedule with increasing design complexity generation after generation.