The AD9870 is a general-purpose IF subsystem which digitizes a low-level 10-300 MHz IF input with a bandwidth of up to 150 kHz. The signal chain of the AD9870 consists of a low-noise amplifier, a mixer, a variable gain amplifier with integral anti-alias filter, a bandpass sigma-delta analog-to-digital converter and a decimation filter with programmable decimation factor. An automatic gain control (AGC) circuit provides the AD9870 with 25 dB of continuous gain adjustment. The high dynamic range of the bandpass sigma-delta converter allows the AD9870 to cope with blocking signals which are as much as 70 dB stronger than the desired signal. Auxiliary blocks include clock and LO synthesizers as well as a serial peripheral interface (SPI) port.
