A multi-stage low power, high dynamic range variable gain amplifier comprises an input stage cascaded with one or more current amplifier stages, whereby the gain of each stage may be independently controlled. The input stage may be comprised of a variable transconductance amplifier using variable emitter...http://www.google.com.tw/patents/US5880631?utm_source=gb-gplus-share專利 US5880631 - High dynamic range variable gain amplifier
