RF Cascade Analyzer
Rolls up a whole receiver or transmitter chain into system-level specs. Enter each stage's gain, noise figure and input third-order intercept (IIP3), and the tool returns the cumulative gain, the cascaded noise figure (Friis), the input- and output-referred IIP3, the noise floor (MDS), and the spurious-free dynamic range (SFDR). The early stages set the noise figure; the later, high-signal stages dominate the linearity — this tool shows the trade-off at a glance.
Equations & Parameters ▸
\(G_{tot}=\textstyle\sum G_k\ \text{(dB)} \qquad F_{tot}=F_1+\dfrac{F_2-1}{G_1}+\dfrac{F_3-1}{G_1G_2}+\cdots\)
\(\dfrac{1}{\text{IIP3}_{tot}}=\dfrac{1}{\text{IIP3}_1}+\dfrac{G_1}{\text{IIP3}_2}+\dfrac{G_1G_2}{\text{IIP3}_3}+\cdots\quad(\text{linear mW})\)
\(\text{MDS}=-174+NF+10\log_{10}B \qquad \text{SFDR}=\tfrac{2}{3}\big(\text{IIP3}-\text{MDS}\big)\)
\(\dfrac{1}{\text{IIP3}_{tot}}=\dfrac{1}{\text{IIP3}_1}+\dfrac{G_1}{\text{IIP3}_2}+\dfrac{G_1G_2}{\text{IIP3}_3}+\cdots\quad(\text{linear mW})\)
\(\text{MDS}=-174+NF+10\log_{10}B \qquad \text{SFDR}=\tfrac{2}{3}\big(\text{IIP3}-\text{MDS}\big)\)
| Gₖ | Gain of stage k (dB). A passive loss is a negative gain. |
| NFₖ | Noise figure of stage k (dB). |
| IIP3ₖ | Input-referred third-order intercept of stage k (dBm). For an amplifier specified by its output intercept, IIP3 = OIP3 − G. |
| IIP2ₖ | Optional input second-order intercept (dBm). Combined with the same power-referred cascade; leave any blank to skip. |
| B | Noise/channel bandwidth (MHz) for the noise floor MDS and SFDR. Optional. |
| SFDR | Two-tone spurious-free dynamic range, referred to a 0 dB output SNR (MDS at SNR = 0). Input P1dB is the ≈ IIP3 − 9.6 dB rule of thumb. |
References: H. Friis, "Noise figures of radio receivers," Proc. IRE 32, 419 (1944). · B. Razavi, RF Microelectronics, 2nd ed., Prentice Hall, 2011 (cascaded IP3). IIP2 combined with the power-referred convention.
Chain Configuration
MHz
Results
Gain & Noise
Total gain—
Cascaded noise figure—
Noise floor (MDS)—
Linearity & Dynamic Range
Input IIP3—
Output OIP3—
Input IIP2—
SFDR—
≈ Input P1dB (IIP3−9.6)—
Diagram