GleichstromOffset

GleichstromOffset, often abbreviated as DC offset, refers to a nonzero average value of an electrical signal. It is the component of a signal that remains constant over time, effectively shifting the waveform away from zero volts. Mathematically, the DC offset is the time average of the signal, vdc = (1/T) ∫ v(t) dt for continuous signals, or the mean of sampled values for discrete signals.

DC offset can arise from imperfect biasing and offset voltages in active components such as operational amplifiers, sensor biases, input bias currents, calibration errors in analog-to-digital or digital-to-analog converters, and asymmetric charging or leakage in coupling networks. Temperature changes, aging, and manufacturing tolerances can cause offset to drift over time.

Measurement and effects depend on the application. In measurement systems with DC coupling, the offset appears as a constant voltage that can skew readings, reduce dynamic range, or saturate subsequent stages. In audio or signal processing, DC offset shifts the entire waveform away from zero, potentially causing speaker or capacitor bias issues, unwanted pops on changes, and degraded accuracy in downstream processing. In control systems, a DC offset can introduce a steady-state error.

Mitigation strategies include hardware approaches such as AC coupling with capacitors, offset trimming and bias cancellation in amplifiers, and using rail-to-rail or mid-supply biasing schemes. Digital methods include removing the mean value in software or during calibration. Precise specification of offset and its drift is common in instrumentation and sensor design.