High Pass Filter Calculator

High Pass Filter Calculator

High Pass Filter Calculator

Understanding High Pass Filters

High Pass Filter

A high-pass filter is an electronic circuit that allows signals with frequencies higher than a specific cutoff frequency to pass through, while attenuating or reducing the amplitude of lower-frequency signals. This makes it an essential tool in audio processing, communication systems, and signal conditioning.

Key Components of a High Pass Filter:

  • Resistance (R): Determines how much the circuit resists current flow, measured in Ohms (Ω).
  • Capacitance (C): Determines the ability of the circuit to store and release electrical energy, measured in Farads (F).

Formula:

The cutoff frequency (fc) is the frequency at which the output signal is attenuated to 70.7% (or -3 dB) of the input signal's amplitude:

fc = 1 / (2πRC)

Steps to Calculate:

  1. Ensure that the resistance (R) and capacitance (C) are in the correct units:
    • Resistance: Convert to Ohms (Ω) if necessary.
    • Capacitance: Convert to Farads (F) if necessary.
  2. Plug the values into the formula: fc = 1 / (2πRC).
  3. Perform the calculation to determine the cutoff frequency.
  4. Adjust the result to the desired frequency unit (e.g., Hz, kHz, MHz).

Example Calculations

Example 1: Standard Calculation

Scenario: Resistance = 10 kΩ, Capacitance = 0.1 μF

  1. Convert units:
    • R = 10 kΩ = 10,000 Ω
    • C = 0.1 μF = 0.1 × 10-6 F = 1 × 10-7 F
  2. Apply the formula: fc = 1 / (2πRC)
  3. fc = 1 / (2 × 3.1416 × 10,000 × 1 × 10-7)
  4. fc = 159.15 Hz

Result: The cutoff frequency is approximately 159 Hz.

Example 2: High Resistance

Scenario: Resistance = 1 MΩ, Capacitance = 100 pF

  1. Convert units:
    • R = 1 MΩ = 1 × 106 Ω
    • C = 100 pF = 100 × 10-12 F
  2. fc = 1 / (2πRC)
  3. fc = 1 / (2 × 3.1416 × 1 × 106 × 100 × 10-12)
  4. fc = 1,591.55 Hz

Result: The cutoff frequency is approximately 1.59 kHz.

Example 3: Low Capacitance

Scenario: Resistance = 470 Ω, Capacitance = 10 nF

  1. Convert units:
    • R = 470 Ω
    • C = 10 nF = 10 × 10-9 F
  2. fc = 1 / (2πRC)
  3. fc = 1 / (2 × 3.1416 × 470 × 10 × 10-9)
  4. fc = 33,862.68 Hz

Result: The cutoff frequency is approximately 33.86 kHz.

Example 4: Small Resistance

Scenario: Resistance = 220 Ω, Capacitance = 2.2 μF

  1. Convert units:
    • R = 220 Ω
    • C = 2.2 μF = 2.2 × 10-6 F
  2. fc = 1 / (2πRC)
  3. fc = 1 / (2 × 3.1416 × 220 × 2.2 × 10-6)
  4. fc = 329.88 Hz

Result: The cutoff frequency is approximately 330 Hz.