An Analytical Approach for Fast Automatic Sizing of Narrow-Band RF CMOS LNAs

Abstract

We introduce a fast automatic sizing algorithm for a single-ended narrow-band CMOS cascode LNA adopting an inductive source degeneration based on an analytical approach without any optimization procedure. Analytical expressions for principle parameters are derived based on an ac equivalent circuit. Based on the analytical expressions and the power-constrained noise optimization criteria, the automatic sizing algorithm is developed. The algorithm is coded using Matlab, which is shown capable of providing a set of design variable values within seconds. One-time Spectre simulations assuming usage of a commercial 90 nm CMOS process are performed to confirm that the algorithm can provide the aimed first-cut design with a reasonable accuracy for the frequency ranging up to 5 GHz. This work shows one way how accurate automatic synthesis can be done in an analytical approach.

An Analytical Approach for Fast Automatic Sizing of Narrow-Band RF CMOS LNAs with a Capacitive Load

“…Z out derivation can be done similarly as the Z in derivation using the equivalent circuit in Figure 2 assuming R si input termination. We present the results here, which are same with those presented in [11].…”

“…Following the same procedure in deriving Y in2 = 1/Z in2 in [11], we get the same Y in2 expression as , Following the same procedure in deriving Y in1 = 1/Z in1 in [11] again, we get the same Y in1 expression as…”

“…To avoid any confusion, we show the assumptions made in this work, which are same with those in [11].…”

“…The derivation procedures and the expressions are exactly same with those in [11]. Here we show the expressions.…”

“…A methodology for providing a set of first-cut design variables with a reasonable accuracy for a narrow-band LNA with a resistive load was previously suggested [11].…”