Filter Considerations

04/16/2009, updated 02/05/2021

(Outline:)

Special Note: Since Filters involve Reactive Components, it would be well to discuss that aspect early.

Applications

• Power Supplies:
  • Removing the AC Component
  • Ripple Reduction
• Audio Circuits:
  • Base Control
  • Treble Control
  • Hiss Reduction
  • "Pass-Over" Unit for Speakers
• Receivers (RF):
  • Tuning
  • "IF Transformers"
  • Detector Circuit (Demodulation)
  • Noise Reduction
  • Bandwidth
• Transmitters:
  • "MO"
  • Audio Limiting
  • Sideband Control
• Oscillators:
  • Audio (Tone Generation)
  • VFO (RF Tuning)
  • BFO (RF Tuning)
  • LMO (Linear Master Oscillator)
  • Stabillity (Drift)
• Analysis:
  • Spectral Analysis
  • Missile Telemetry
    • (Frequency and Energy Subjected to Missile Payloads)
• General Types:
  • Low-Pass
  • High-Pass
  • Bandpass
  • Notch (Bandpass-Reject)
• Configuration:
  • L-Type
  • T-Type
  • Pi-Type
  • Unbalanced
  • Balanced
• Uses: (see "General Types", above)
  • Signal Pass (Desired Signal)
  • Signal Block (Undesired Signal)
• Terminology:
  • Bandwidth
  • "Q"
  • Tuneable
  • Stability (Drift)
  • Signal Loss
  • Quality Degradation
• Special RF Considerations:
  • Gamma-Match
  • Hairpin Tuning
  • Shorted "Quarter-Wave" Stub
    
• Components:
  • Inductors:
    • Solid-Iron-Core
    • Powdered Iron-Core
    • Air-Core
    • "Q"
    • "Skin-Effect"
  • Transformer-Coupled
  • Capacitors
    • Electrolytic
    • Non-Electrolytic
  • Resistance
  • Vacuum (Tunable) Capacitors
    
• Special Types:
  • "Twin-T"
  • mDerived
  • Constant-K
  • Bessel
  • Butterworth
  • Tracking Filter