Abstract
Two mu-power VGA circuits targeting the body sensor network applications are designed in 0.18-mu m CMOS technology. By employing a digitally switched-load gain variation scheme, the gain of the first VGA and the second VGA can be varied linearly from -18.5dB to +24.5dB, and from +16dB to +54dB, respectively. Input-referred noise at maximum gain mode is less than 17nV/root Hz and the current consumption is less than 400 mu A from a 1.8V supply for both circuits. The VGAs exhibit excellent linearity in terms of gain variation and gain compression. Small silicon area is achieved by avoiding bulky passive components.