Unity-Gain Phase Splitter

Equal collector and emitter resistors provide opposite-polarity AC outputs with similar amplitudes.

Circuit operation

The base receives a 0.5 V peak sine wave around 2.5 V. Equal 1 kΩ collector and emitter resistors convert the same changing transistor current into opposite voltage changes.

Expected behavior

$$\Delta V_C\approx-\Delta I_C R_C$$ $$\Delta V_E\approx+\Delta I_E R_E$$

The collector and emitter have different DC levels but nearly equal AC amplitudes with opposite phase. The equality is approximate because emitter current includes base current and the transistor has finite gain.

Reading the results

The first voltage probe is green and the second is red. Additional voltage traces use distinct colors. Current probes, when present, start with blue and then purple. The chart opens with separate traces on a fixed time window; the table retains the same probe order. Zoom to extents includes the complete schematic.

The saved transient runs for 4.0 ms with a maximum step of 1.00 µs. Compare settled cycles after startup and use time-axis cursors to measure delays or periods.

Try a change

Set RE to 2 kΩ; compare the reduced emitter current and changed gain or bias. Restore the saved values after comparing the result.

Model limits

These are generic transistor models, not a specific manufactured part. The bipolar models use nominal forward current gain 100 with illustrative junction capacitances and transit times. Device mismatch, temperature drift, layout parasitics, breakdown and detailed noise are not represented. The schematic and component properties expose the values used.