A 5GHz LNA with new compact gain controllable active balun for ISM band applications

A low noise amplifier (LNA) with a new gain controllable on-chip active balun has been designed for a 5 GHz industrial scientific medical (ISM) band direct conversion receiver (DCR). The active balun provides good gain and phase matching with LNA gains of 19.5 dB and 12 dB in high gain and low gain modes, respectively, while achieving a noise figure of 3 dB and an IIP/sub 3/ of -11.5 dBm. In the low gain mode the LNA provides 50% power savings by using 15mW from a 3V supply.