Room-Temperature CMOS LNA With Non-50 Signal-Source Impedance

This paper presents a wideband low-noise amplifier (LNA) designed to be used as the first stage of the receiver in the Square Kilometer Array radio telescope. The LNA design procedure and its layout features are discussed. The noise figure optimization procedure determines the signal-source resistance that results in reduced noise figure. When used in the radio telescope, the required signal-source resistance will be presented by the telescope custom-made antenna elements. The LNA, designed in 90 nm bulk CMOS, achieves sub-0.2 dB noise figure from 800 MHz to 1400 MHz, return loss of more than 11 dB, gain ( 21) of more than 17 dB driven into a 50 load, output 1 dB compression point of 2 dBm, output IP3 of 12 dBm, and output IP2 of 22 dBm while consuming 43 mA from a 1 V supply. In the LNA implementation presented in this paper the load choke inductor and the source inductor are integrated whereas the gate-, bias-, and the choke-inductor between two transistors of the cascode are external. The noise figure of the presented LNA is to our knowledge the lowest noise figure achieved by a power matched wideband CMOS LNA at room temperature.