superregenerative

Superregenerative receivers achieve very high gain and sensitivity with regenerative feedback intermittently interrupted by a quench oscillator. The RF stage is biased near saturation, and regeneration is alternately turned on and off. The quench oscillator modulates the feedback, creating bursts of RF energy that are detected by an envelope detector to recover the audio or data signal.

Operation: The core stage is usually a single transistor or vacuum tube with a tuned input and a feedback path. A separate quench oscillator drives the loop, switching regeneration at a rate in the kilohertz to tens of kilohertz range. The resulting RF pulses carry the modulated information, which is extracted by subsequent audio or data stages.

Design considerations: High sensitivity and broadband response come with relatively few parts, but the topology suffers from poor selectivity and stability. Regeneration can be unstable and distortion-prone, and alignment is sensitive to supply voltage, temperature, and device characteristics. These drawbacks helped drive the shift to more stable technologies for general use.

History and use: The circuit emerged in the early radio era and saw use in some AM receivers and other simple RF systems, as well as remote controls and hobbyist designs. Today, superregenerative receivers are largely of historical interest or employed only in very low-cost or niche applications where simplicity outweighs performance.