Analysis and Design of a 60 GHz Wideband Voltage-Voltage Transformer Feedback LNA

To cope with the problem of instability and imperfect reverse isolation, a millimeter-wave voltage-voltage transformer feedback low noise amplifier has been analyzed, designed, and measured in CMOS 65 nm technology. Analytical formulae are derived for describing the stability, gain, and noise in this circuit topology. An analogy with the classic concept of Masons´s invariant is used to illustrate how the transformer feedback provides the required reverse isolation in the LNA. Based on the developed theoretical analysis, the circuit is implemented as a fully integrated 60 GHz two-stage differential low noise amplifier in 65 nm CMOS technology. A flat gain of 10 dB is achieved over the entire 6 GHz bandwidth. The measured noise figure is 3.8 dB.