Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences


UC Berkeley


2009 Research Summary

Broadband LNA Design Employing Noise and Distortion Cancellation (COGUR)

View Current Project Information

Ali Niknejad and Wei-Hung Chen


One of the key challenges in designing multi-standard multi-mode front-end circuits is the high dynamic range requirement over a wide frequency range. Even in a "digital" receiver application, employing discrete-time signal processing, a linear front-end amplifier is required to reject the noise and relax the performance of the subsequent samplers. The straightforward solution for multi-standard multi-mode front-ends employs reactive tuning and multiple receiving paths at the cost of die and board area, high pin count, and lack of reconfigurability. Recent demonstration of ultra-wideband (UWB) LNAs ranging from several hundreds of MHz up to 10 GHz suggests an alternative that uses a single circuit for contiguous broadband signal receiving and has achieved comparable performances to its narrow-band counterparts by exploiting high fT /fmax transistors available from nano-scale CMOS.

In this project, broadband techniques of noise and distortion cancellation are investigated and incorporated with the common-gate input stage to deliver the simultaneous low noise figure and high IIP3 over a wide frequency range. The role of third-order distortion due to the second-order interaction of the linear and second-order nonlinear outputs is identified and also accounted for in the distortion cancellation design. The scheme is verified by a 0.8~2.1 GHz CMOS LNA in 0.13 µm technology with a measured peak IIP3 of +16 dBm and a noise figure below 2.6 dB. A modified distortion cancellation is applied to a second LNA design aiming to eliminate the IIP3 2-tone frequency dependency observed in the first circuit. The new LNA is carried out in 65 nm CMOS and achieves comparable dynamic range with an extended bandwidth up to 5 GHz in the simulation.

Figure 1
Figure 1: Chip microphotograph of the 0.8~2.1 GHz LNA

W.-H. Chen et al., "A Broadband Highly Linear CMOS LNA Employing Noise and Distortion Cancellation," Proc. IEEE RFIC Symposium, Honolulu, HI, June 2007, pp. 61-64.