Zero power bypass variable gain splitter for TV tuner

A fully integrated 42-870 MHz TV splitter based on switched RF-VGA amplifiers with an unpowered bypass mode is introduced. The splitter is intended for DVD-Recorder or set-top boxes (STB) applications. The circuit integrates a novel RF bypass switch function based on a native MOS device which requires zero DC power for its operation. The switch mechanism and gain control are described; it features power detection and continuous self-adjusted gains. The broadband input impedance matching network suitable for this approach is based on pseudo transmission line. The VGA exhibits an input IP2 and IP3 of respectively 85 dBmV and 73 dBmV, while the noise figure is 5.5 dB with 9 dB gain. The unpowered bypass mode has -3 dB insertion loss The chip is fabricated in 0.18 ¿m CMOS technology and dissipates 175 mW from a 3.3 V supply.