Figure 6: Functional block diagram (left) and photograph (right) of RTL-SDR.
It gets its RF functionality from Rafael Microelectronics make R820T chip. R820T is a RF tuner IC which consists of a mixer and digitally controlled VCO along with variable gain amplifier and filter stages before and after the mixer stage. VCO oscillator frequency, amplifiers gain and filter bandwidth of R820T are controlled by the Realtek RTL2832U chipset over I2C serial bus. RTL2832U also digitize the down converted baseband IF signals using inbuilt DDC and sends 8 bit IQ data over USB bus to the PC for further processing. Key specifications of RTL-SDR are tabulated in Table 5. More details of RTL-SDR hardware can be obtained from [1].
Table 5: RTL-SDR Specifications