A　low　power　hybrid　PG_Filter-AGC　analog　baseband　is　presented,　including　a　programmable　filter　(PG_filter)　and　an　auto　gain　control　core　(AGC_core).　It　adopts　the　digital-plus-analog　mixed　gain　control　methodology,　resulting　in　an　effective　power　reduction　and　a　decibel　gain　error　improvement.　To　further　reduce　the　power　of　the　AGC_core,　a　low　power　Variable　Gain　Amplifier　(VGA)　adopting　sub-threshold　design　methodology　is　presented.　Furthermore,　a　self-adaptive　threshold　voltage　compensation　(SATC)　scheme　is　proposed　to　guarantee　the　good　anti-process　variation　performance　for　sub-threshold　design　methodology.　The　hybrid　analog　baseband　has　been　fabricated　under　SMIC　0.18　mu　m　CMOS　process,　with　a　die　size　of　0.45　mm(2),　where　the　AGC_core　occupies　an　area　of　0.28　mm(2).　The　test　results　demonstrate　a　total　power　of　4.1　mW,　where　the　AGC_core　consumes　a　power　of　0.39　mW.　A　consecutive　gain　dynamic　range　of　80　dB,　with　a　decibel　gain　error　small　than　+/-　0.39　dB,　is　achieved　and　the　cutoff　frequency　ranges　from　0.5MHz　similar　to　30　MHz.