BCM3421

Description

The BCM3421 is a highly integrated, advanced direct conversion, single-chip silicon tuner. BCM3421 integrates the global tuning function, including selectivity, and supports 64-QAM, 256-QAM, and 1024-QAM digital cable modem applications. The input signal is first driven to the LNA with wideband AGC and then filtered and fed to the image rejection mixer. The LO of BCM3421 signal feeds the second input of the mixer which downconverts the RF signal to a low 4-MHz IF frequency. The IF signal is then filtered (channel selectivity) and shaped to be connected to the channel decoder inputs. There is no need for an external SAW filter. Additionally, the Voltage Controlled Oscillator (VCO) is fully integrated with no external tank component.

The BCM3421 is specifically designed for use with Broadcom's industry-leading single-chip cable modem devices. With a low BOM cost and a proven reference design, it provides a better alternative to traditional can tuners. The BCM3421 supports an IF output frequency range of 4 MHz, 4.5 MHz, and 5 MHz, enabling one device to support both DOCSIS® and EuroDOCSIS™ standards.