The R820T and improved R820T2 (and related R828D) from Rafael Micro are the most
common tuner chips paired with the RTL2832U in
RTL-SDR dongles. They provide the RF front-end and
mixer/local oscillator.1
The R820T/R820T2 is the most common RTL-SDR tuner chip — it amplifies and mixes RF down for the ADC.
Overview
The tuner amplifies and shifts the selected band down to a low frequency the RTL2832U
can digitise, covering roughly 24 MHz–1.7 GHz. Tuner quality affects sensitivity and
overload behaviour.
Relevance to SDR
The tuner sets the dongle’s frequency range and much of its noise performance, important
when chasing weak signals.
Sources
RTL-SDR — Wikipedia, on the R820T/R820T2 tuners commonly paired with the RTL2832U. ↩
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