Subject overview
Filters
Unloaded RC and RL high-pass and low-pass filters, cutoff frequency, gain and output phase.
01 RC High-Pass
Variables
- φphase angle
- radradian
- Rresistance
- Ωohm
- XCcapacitive reactance
- Ωohm
- aattenuation
- dBdecibel
- Ccapacitance
- Ffarad
- Uininput RMS voltage
- Vvolt
- Uccapacitor RMS voltage
- Vvolt
- Uoutoutput RMS voltage
- Vvolt
- fccutoff frequency
- Hzhertz
- ffrequency
- Hzhertz
- gvoltage gain
- 1dimensionless
Key Formulas
The transfer function is the complex ratio of output to input. With x = f/fc, ideal first-order low-pass and high-pass responses follow directly from the complex voltage divider. Their cutoff magnitude is 1/√2 and their asymptotic slope magnitude is 20 dB per decade.
Unloaded ideal first-order filter; source impedance zero. Output across R. f, R and C > 0. Phase is output relative to input.
Calculate
Type prefixes directly: 1.5k, 250m or 20u. Results: 3 significant figures.
Unloaded ideal first-order filter; source impedance zero. Output across R. f, R and C > 0. Phase is output relative to input.
Enter the required input values to calculate.
Schematic curve; no numerical scale.
Schematic curve; no numerical scale.
02 RC Low-Pass
Variables
- φphase angle
- radradian
- Rresistance
- Ωohm
- XCcapacitive reactance
- Ωohm
- aattenuation
- dBdecibel
- Ccapacitance
- Ffarad
- Uininput RMS voltage
- Vvolt
- Uoutoutput RMS voltage
- Vvolt
- fccutoff frequency
- Hzhertz
- ffrequency
- Hzhertz
- gvoltage gain
- 1dimensionless
Key Formulas
The transfer function is the complex ratio of output to input. With x = f/fc, ideal first-order low-pass and high-pass responses follow directly from the complex voltage divider. Their cutoff magnitude is 1/√2 and their asymptotic slope magnitude is 20 dB per decade.
Unloaded ideal first-order filter; source impedance zero. Output across C. f, R and C > 0. Phase is output relative to input.
Calculate
Type prefixes directly: 1.5k, 250m or 20u. Results: 3 significant figures.
Unloaded ideal first-order filter; source impedance zero. Output across C. f, R and C > 0. Phase is output relative to input.
Enter the required input values to calculate.
Schematic curve; no numerical scale.
Schematic curve; no numerical scale.
03 RL High-Pass
Variables
- φphase angle
- radradian
- Rresistance
- Ωohm
- XLinductive reactance
- Ωohm
- aattenuation
- dBdecibel
- Linductance
- Hhenry
- Uininput RMS voltage
- Vvolt
- Uoutoutput RMS voltage
- Vvolt
- fccutoff frequency
- Hzhertz
- ffrequency
- Hzhertz
- gvoltage gain
- 1dimensionless
Key Formulas
The transfer function is the complex ratio of output to input. With x = f/fc, ideal first-order low-pass and high-pass responses follow directly from the complex voltage divider. Their cutoff magnitude is 1/√2 and their asymptotic slope magnitude is 20 dB per decade.
Unloaded ideal first-order filter; source impedance zero. Output across L. f, R and L > 0. Phase is output relative to input.
Calculate
Type prefixes directly: 1.5k, 250m or 20u. Results: 3 significant figures.
Unloaded ideal first-order filter; source impedance zero. Output across L. f, R and L > 0. Phase is output relative to input.
Enter the required input values to calculate.
Schematic curve; no numerical scale.
Schematic curve; no numerical scale.
04 RL Low-Pass
Variables
- φphase angle
- radradian
- Rresistance
- Ωohm
- XLinductive reactance
- Ωohm
- aattenuation
- dBdecibel
- Linductance
- Hhenry
- Uininput RMS voltage
- Vvolt
- Uoutoutput RMS voltage
- Vvolt
- fccutoff frequency
- Hzhertz
- ffrequency
- Hzhertz
- gvoltage gain
- 1dimensionless
Key Formulas
The transfer function is the complex ratio of output to input. With x = f/fc, ideal first-order low-pass and high-pass responses follow directly from the complex voltage divider. Their cutoff magnitude is 1/√2 and their asymptotic slope magnitude is 20 dB per decade.
Unloaded ideal first-order filter; source impedance zero. Output across R. f, R and L > 0. Phase is output relative to input.
Calculate
Type prefixes directly: 1.5k, 250m or 20u. Results: 3 significant figures.
Unloaded ideal first-order filter; source impedance zero. Output across R. f, R and L > 0. Phase is output relative to input.
Enter the required input values to calculate.
Schematic curve; no numerical scale.
Schematic curve; no numerical scale.