A highly selective LNTA capable of large-signal handling for RF receiver front-ends

Abstract

To achieve ultimately flexible multi-core radio operation, wide-band receiver RF front-ends must be robust against interference well in excess of the requirements usually specified by a radio standard. In this paper, a highly selective, very linear low-noise transconductance amplifier (LNTA) capable of large-signal handling for current-mode receiver (RX) front-ends is proposed and implemented in 65-nm CMOS. It is shown that by combining on-chip highQ bandpass filters with a push/pull class-AB common-gate stage, a measured 1-dB desensitization point (B1dB) and large-signal IIP3 of +8 dBm and +20 dBm, respectively, can be achieved. In addition, by applying a noise cancellation technique, via an auxiliary push/pull class-AB common-source stage, the proposed LNTA measures a moderate NF of 5.9 dB, which is a very competitive number for such high value of B1dB. The circuit consumes 7.5 mA at 1.5 V.