Electrical & Electronics Engineering / Active Butterworth Filter
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LABORATORY 15 · ELECTRICAL & ELECTRONICS ENGINEERING

Second-Order Sallen-Key Active Butterworth Low-Pass and High-Pass Filter Frequency Response

Measure the frequency response, cut-off frequency (f_c), stopband roll-off attenuation rate (-40 dB/decade), and phase shift of a second-order active Sallen-Key low-pass filter. Explore interactive circuit analysis, electronics simulation, and electrical engineering telemetry.

CIRCUIT ANALYSIS · ANALOG · DIGITAL · MACHINES · POWER SYSTEMS · CONTROL & INSTRUMENTATION

Your virtual electrical & electronics engineering laboratory.

STOPBAND ATTENUATION RATE—
INSTRUMENTATION TELEMETRY

Ready to sample with Log Frequency = 0.6 decade.

0.6 decade
Calibrated Sallen-Key Active Filter Workstation baseline operating point stabilized at 25.0 °C

Adjust Log Frequency, then execute electrical instrumentation acquisition.

Electrical telemetry is sampled with calibrated high-precision instruments using 64-bit IEEE 754 precision buffers. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity circuit and power system modeling.

Electrical engineering assumptions and boundary limits

Assumes ideal linear operating conditions without thermal breakdown or non-linear core saturation Calibrated using the Sallen-Key Active Filter Workstation under controlled temperature and 64-bit IEEE 754 precision instrumentation buffers. Ordinary least-squares regression yields R² > 0.99999.

Laboratory apparatus & testing equipment.

Active Butterworth Filter Precision Workstation

Provides regulated excitation, calibrated terminal access, and low-parasitic interconnects for maximally flat passband, complex conjugate poles & stopband rejection.

True-RMS Digital Multimeter (6.5-digit Keysight / Fluke)

Measures terminal voltages, branch currents, and precision DC/AC parameters with ±0.0035% baseline accuracy.

Dual-Channel Digital Storage Oscilloscope (100 MHz, 1 GSa/s)

Captures time-domain waveforms, phase shifts, transient dynamics, and harmonic spectra for active butterworth filter.

Regulated Linear DC / AC Variable Power Source

Supplies low-noise, ripple-free voltage and current excitation with adjustable current limiting.

Calibrated Decade Resistance & Component Substitution Box

Provides precision 0.1% tolerance standard passive values to establish calibrated log frequency conditions.

Four-Terminal Kelvin Lead Wire & BNC Coaxial Cable Set

Minimizes lead resistance, inductive pickup, and ambient EMI interference across all test ports.

FOLLOW THE METHOD

A reason behind every step.

Measure the frequency response, cut-off frequency (f_c), stopband roll-off attenuation rate (-40 dB/decade), and phase shift of a second-order active Sallen-Key low-pass filter. Standardized parameter settings: 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 decade.

  1. Visual Inspection & Pre-Flight Zero Tare: Inspect all circuit connections, breadboard jumpers, and terminal blocks. Verify that instrument ground planes are tied to earth and execute zero tare on all digital meters.
  2. Excitation Source & Baseline Calibration: Energize the regulated supply, set baseline operating thresholds, and calibrate the log frequency using the precision standard reference meter.
  3. Systematic Parameter Variation & Settling: Increment the log frequency systematically across the designated experimental range (0.2 to 1.2 decade), permitting thermal settling at each setpoint.
  4. Multi-Meter & Oscilloscope Waveform Acquisition: Record the primary output metric (Stopband Attenuation Rate) alongside auxiliary telemetry. Verify waveform symmetry, DC offset, and harmonic integrity on the oscilloscope.
  5. Cross-Validation & Redundant Trial Verification: Execute repeated forward and reverse sweeps to detect hysteresis, thermal drift, or non-linear saturation effects across the device under test (DUT).
  6. Shutdown, De-energization & Data Archival: Reduce source excitation smoothly to zero, de-energize all primary supplies, discharge residual capacitive elements, and export raw telemetry to the data buffer.
YOUR NOTEBOOK · 0 OBSERVATIONS

Turn measurements into electrical engineering insight.

See a complete example report ↗

Points are your recorded observations. The solid regression line validates Active Butterworth Filter mathematical scaling.

LINEAR REGRESSION FIT · y = mx + b
Gain = -40.0000 · log₁₀(f/f_c)
#Log Normalized Frequency log₁₀(f/f_c) (decade)Stopband Attenuation Rate (dB)Normalized frequency decade log₁₀(f/f_c)Stopband attenuation (dB)

No readings yet. Execute an electrical trial and record it.

CHECK YOUR UNDERSTANDING

Explain what the circuit metrics mean.

Question 1: In the study of Active Butterworth Filter, the primary dependent variable measured is:

Question 2: The mathematical relationship governing Active Butterworth Filter is modeled as:

Question 3: The target benchmark parameter derived from regression analysis is:

Question 4: Which instrumentation technique effectively eliminates lead wire resistance error?

THEORY AND ELECTROMAGNETIC CONTEXT

Electrical engineering background & physical principles.

The experimental analysis of second-order sallen-key active butterworth low-pass and high-pass filter frequency response investigates the electrotechnical behavior of sallen-key active filter workstation. This university laboratory module focuses on maximally flat passband, complex conjugate poles & stopband rejection, establishing accurate mathematical transfer characteristics across standard operational domains.

Gain = -40.0000 · log₁₀(f/f_c)

Calibrated using the Sallen-Key Active Filter Workstation under controlled temperature and 64-bit IEEE 754 precision instrumentation buffers. Ordinary least-squares regression yields R² > 0.99999.