Engineering Knowledge Base
Turn complex specifications into actionable engineering decisions for selection, replacement, and evidence review.
Is Back Drilling Worth It: Quarter Wave Resonance of the Via Stub, Depth Tolerance and Three Alternative Paths
A through hole via on a multilayer board spans the whole stackup, while the signal usually changes layer on only two or three of those layers. The unused barrel below the connection point is the stub. It is irrelevant at low frequency, but in a link running above ten gigabits per second it becomes an unterminated transmission line that resonates at a quarter wavelength and carves a deep notch into the channel response. This article starts from how the stub length is calculated, quantifies the relationship between resonant frequency and insertion loss, explains the controlled depth re-drilling process of back drilling and the constraints between bit diameter and remaining stub, analyses how depth tolerance and layer to layer registration turn a design target into a distribution across the panel, compares the three alternatives of blind and buried vias, stackup scheduling and simply not drilling, and closes with an actionable decision threshold and verification method.
Diagnosing Noise and Improving WLAN Receiver Sensitivity
A high WLAN data rate is of little value if internal device noise enters the 2.4 GHz or 5 GHz receive band. Effective improvement starts by identifying the sour…
Selecting Chip Ferrite Beads for High Temperature Automotive Electronics
Automotive electronics combine wider noise spectra, demanding EMC limits, and elevated operating temperatures. A chip ferrite bead can provide high-frequency im…
Analog and Digital Filter Design for Precision ADC Signal Chains
Filtering in a precision ADC system must satisfy frequency-domain rejection, input settling, and response-time requirements together. Analog filters determine w…
Assessing and Suppressing Low Frequency Flicker Noise in Precision Measurements
For signals near dc and measurements with narrow bandwidths, 1/f noise can become an accuracy bottleneck. Because the noise overlaps the wanted signal at low fr…
Quantifying the Noise Penalty of an ADC Driver Amplifier
An ADC driver can provide gain, impedance transformation, and single-ended to differential conversion, but its noise also reduces system SNR. A direct way to qu…
Capacitive PGAs in Precision ADC Sensor Interfaces
Strain gauges and temperature sensors often produce signals too small to use the full ADC input range directly. A PGA increases their amplitude, but internal no…
RF Noise Suppression and Low Distortion in Smartphone Audio Filters
An audio noise suppression filter in a smartphone serves two linked purposes: reducing noise coupled from audio wiring into wireless receivers and preserving th…
YAGEO RC0402FR-0784K5L 84.5 kΩ Resistor: Specifications, Derating, and Replacement Selection
RC0402FR-0784K5L is an 84.5 kΩ thick-film chip resistor in YAGEO’s RC_L general-purpose series. It uses the 0402 imperial (1005 metric) package and has a ±1% re…
Why Voltage-Reference Noise Matters in High-Resolution ADC Systems
Why Voltage-Reference Noise Matters in High-Resolution ADC Systems In converters above 24 bits, the ADC itself is often no longer the only noise bottleneck. The…
Using Zero-Drift Amplifiers in Wider-Bandwidth Applications
Using Zero-Drift Amplifiers in Wider-Bandwidth Applications Zero-drift amplifiers are often treated as devices for slow, dc-oriented signal chains. That view is…