# A g\({}_{m}\)/I\({}_{\rm D}\)-Based Low-Power LNA for Ka-Band Applications
## 2 Design Procedure
Their area could be included in the definition of the FoM if the designer wants to account for them in a fairer comparison. These parameters enable us to assess and compare the quality of the different cases. As shown in Table 1, in the case of IC\({}_{1}\), a high value of the FoM\({}_{IC}\) is achieved with very low power consumption, but with unfavorable results, the NF is significantly high and the gain is under 10 dB. However, the FoM\({}_{IC1}\) = 5.7 indicates that the LNA is more efficient in generating a high gain and low NF performance from the current drawn. For IC\({}_{1}\), the LNA shows a maximum gain of 8.6 dB and an NF\({}_{min}\) of 3.9 dB, but it draws only 0.67 mA. Whereas the power consumption of solution IC\({}_{1}\) is remarkable, the gain and NF values are not in line with state-of-the-art K-band LNA designs. A gain above 10 dB and NF under 3 dB with \(\sim\)10 mA are considered state-of-the-art results. Notice the results for IC\({}_{2}\), with a G\({}_{max}\) increment of more than 5.5 dB compared to IC\({}_{1}\) (to 14.2 dB) and NF\({}_{min}\) reduction of 2 dB (to 1.9 dB), with a three-times-higher drain current (2.2 mA) required compared to IC\({}_{1}\). Considering similar works available in the literature, these values of G\({}_{max}\) and NF\({}_{min}\) are closer to state-of-the-art K-band LNAs. As seen for IC\({}_{3}\), the values of G\({}_{max}\) and NF\({}_{min}\) are improved further to 17 dB and 1.4 dB, respectively, but the current drawn increases as well. The required I\({}_{D}\) is three times that required to bias the IC\({}_{2}\) LNA, yet the NF\({}_{min}\) is only improved by 0.5 dB, and the maximum gain, by less than 3 dB. In the case of IC\({}_{2}\), slightly inferior results are obtained compared to IC\({}_{3}\), but with a much higher FoM\({}_{IC}\) value and better power consumption. On the other hand, comparing IC\({}_{1}\) to IC\({}_{2}\), the improvement in FoM\({}_{IC}\) or power consumption is not as significant, meaning IC\({}_{2}\) is not as efficient as IC\({}_{1}\)  
\[IC=\frac{I_{DS}}{I_{spec\square}\cdot W/L} \tag{1}\]3 Maximum gain G\({}_{max}\) and NF\({}_{min}\) as a function of the inversion coefficient. yet the results are inferior to state-of-the-art K-band LNAs. In the case of IC\({}_{3}\), the results can be further improved, but with a strong impact on the LNA's power consumption with small gains in performance. Ultimately, the decision is to proceed with the layout design for IC\({}_{2}\) = 1.76 \(\upmu\)A, as it provides enough gain and NF to be in line with state-of-the-art solutions with the best trade-off between performance and power consumption, which will be explained in more detail in the following section. \[IC=\frac{I_{DS}}{I_{spec\square}\cdot W/L} \tag{1}\]4  
After assembling the schematic, the DC operating point of the circuit is analyzed to verify the previously calculated values. There is an expected deviation in the DC parameters, since the FETs were simulated in a common-source configuration with a V\({}_{DS}\) of 0.9 V. However, in the cascode the effective V\({}_{DS}\) for each FET is reduced to \(\sim\)0.45 V, and due to the nature of short-channel devices, there is a drain current mismatch. Therefore, V\({}_{GS}\) must be adjusted to ensure the drain current targeted value. Now, the LNAs' matching components can be calculated. To bring the \(Z_{11}\) and \(Z_{opt}\) to the center of the Smith chart, the values of L\({}_{source}\), L\({}_{gate}\), and L\({}_{drain}\) inductors (see Figure 2) are calculated. Additionally, a C\({}_{out}\) value of 50 fF has been established for all three cases to improve the S\({}_{22}\).