GRF640x Digital Step Attenuators Guerrilla RF GRF640x Digital Step Attenuators (DSAs) feature a RAPID FIRE® hybrid control mechanism that combines the speed of parallel programming with the simplicity and convenience of a single control line. The GRF640x DSA family utilizes two dedicated registers to store separate attenuation states. Toggling the RFA bit allows the DSA to switch between the primary and secondary states quickly. This fast switching circumvents the delays commonly associated with serial programming. Depending on the SPI clock rate, these delays can be as long as 1600ns. To match the RFA switching speeds, traditional DSAs must utilize parallel programming modes with seven dedicated control lines. This additional I/O not only requires larger packaging but also complicates signal routing.