I have token a part in a project, where a VGA chip named HMC960LP4E was selected. I have drawed a PCB according to hmc960lp4e_eval_pcb_schematic. However, I cannot see the Varible Gain form the chip. Actually, I just want to control the gain by the parallel ports without SPI. So I utilised the default value in the registersinstead of changing them via SP
I bus. What's worse, the signal with power -30dBm found its power reduced to -65dBm after through the chip. I have teste d both software and hardware for many times. But the result was always that bad without any gain. I have no idea about this. Thanks fort your answer.