RF Frequency Scaling

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RF Frequency Scaling is an empirical observation that the record maximum oscillation frequency (f_max) of state-of-the-art RF transistors has grown exponentially over time, increasing by approximately 1.6× per decade. It was first formally proposed by Asif Alam and Muhmmad Shah Alam in a peer-reviewed study published in IEEE Access.^[1]

The observation has been described as an RF analogue to Moore's Law in digital electronics,^[1] similar in spirit to other empirical scaling laws such as Dennard scaling,^[2] Edholm's Law,^[3] and Koomey's Law^[4] in other domains of electronics and communications.^[5]

Background

RF technology has progressed from kilohertz spark gaps to multi-gigahertz integrated circuits over more than a century.^[6]^[7] This climb has enabled global communications,^[8] automotive radar,^[9] biomedical imaging,^[10] and spaceborne sensing.^[11]

Despite the existence of scaling principles in other domains, including Moore's Law for transistor density,^[5] Dennard scaling for power density,^[2] Nielsen's Law for internet bandwidth,^[12] Koomey's Law for energy efficiency,^[4] Cooper's Law for spectral efficiency,^[13] and Edholm's Law for wireless data rates^[3], no equivalent unified scaling law had previously been established for RF transistor performance.^[1]

The Observation

By analyzing over 1,000 published RF transistor results spanning 1985–2025, covering CMOS, III–V HEMTs, SiGe HBTs, and InP HBTs,^[14]^[15]^[16]^[17] Alam and Alam found that the record f_max, the frequency at which a transistor can no longer deliver power gain^[18]^[19], grows by approximately 1.6× every decade.^[1]

Historically, every decade the state-of-the-art transistor f_max record has increased by roughly 1.6×, tracing an exponential frontier of RF performance.

Comparison with Moore's Law

Moore's Law predicts a doubling of transistor density approximately every two years^[5], a much faster rate than the RF scaling trend. This disparity arises because RF performance depends on gain, noise, linearity, and power handling, each constrained by analog device physics and electromagnetic behavior, rather than simple integration density.^[1] In RF circuits, interconnect, substrate, and packaging all leak into the signal path, causing many improvements to enter as weak powers of geometry.^[1]

Physical Limits

Carrier transport limits,^[20]^[21] atmospheric propagation windows,^[22] and packaging constraints^[23] are expected to cause conventional electronic RF transistor technologies to approach a physical ceiling in the sub-THz and beyond range.^[1]

References

[1]
A. Alam and M. S. Alam, "KHz to THz: Unified trends in RF frequency scaling," IEEE Access, vol. 14, pp. 751–762. DOI: 10.1109/ACCESS.2025.3646610.
[2]
R. H. Dennard et al., "Design of ion-implanted MOSFET's with very small physical dimensions," IEEE J. Solid-State Circuits, vol. JSC-9, no. 5, pp. 256–268, Oct. 1974.
[3]
S. Cherry, "Edholm's law of bandwidth," IEEE Spectr., vol. 41, no. 7, pp. 58–60, Jul. 2004.
[4]
J. Koomey et al., "Implications of historical trends in the electrical efficiency of computing," IEEE Ann. Hist. Comput., vol. 33, no. 3, pp. 46–54, Mar. 2011.
[5]
G. E. Moore, "Cramming more components onto integrated circuits," Electronics, vol. 38, no. 8, pp. 114–117, Apr. 1965.
[6]
J. D. Kraus and D. A. Fleisch, Electromagnetics With Applications. Boston, MA: McGraw-Hill, 1999.
[7]
T. S. Rappaport et al., "Wireless communications and applications above 100 GHz: Opportunities and challenges for 6G and beyond," IEEE Access, vol. 7, pp. 78,729–78,757, 2019.
[8]
E. Dahlman, S. Parkvall, and J. Skold, 5G NR: The Next Generation Wireless Access Technology, 2nd ed. London: Academic, 2021.
[9]
M. I. Skolnik, Introduction to Radar Systems, 3rd ed. New York: McGraw-Hill, 2001.
[10]
S. K. Koul and P. Kaurav, Sub-Terahertz Sensing Technology for Biomedical Applications. Cham: Springer, 2022.
[11]
B. Elbert, The Satellite Communication Applications Handbook, 2nd ed. Norwood, MA: Artech House, 2004.
[12]
J. Nielsen, "Nielsen's law of internet bandwidth," Tech. Rep., Apr. 1998.
[13]
M. Cooper, Cooper's Law, 2010.
[14]
J. D. Preez, S. Sinha, and K. Sengupta, "SiGe and CMOS technology for state-of-the-art millimeter-wave transceivers," IEEE Access, vol. 11, pp. 55,596–55,617, 2023.
[15]
T. E. Kazior, G. M. Jones, and T.-H. Chang, "Emerging millimeter-wave device technology — Next generation GaN and beyond," in IEEE MTT-S Int. Microw. Symp. Dig., Jun. 2022, pp. 287–290.
[16]
M. Samnouni et al., "1.2 THz maximum frequency of oscillation achieved by using 75 nm gate length and asymmetric gate recess for InGaAs/InAlAs PHEMT," in Proc. Compound Semiconductor Week (CSW), 2019, pp. 1–2.
[17]
W. Chakraborty et al., "Cryogenic RF CMOS on 22 nm FDSOI platform with record f_T and f_MAX," in Proc. Symp. VLSI Technol., Jun. 2021, pp. 1–2.
[18]
I. J. Bahl and P. Bhartia, Microwave Solid State Circuit Design. New York: Wiley, 1988.
[19]
B. Saha et al., "Reliable technology evaluation of SiGe HBTs and MOSFETs: F_MAX estimation from measured data," IEEE Electron Device Lett., vol. 42, no. 1, pp. 14–17, Jan. 2021.
[20]
A. M. Ganose et al., "Efficient calculation of carrier scattering rates from first principles," Nature Commun., vol. 12, no. 1, Art. no. 2222, Apr. 2021.
[21]
E. Johnson, "Physical limitations on frequency and power parameters of transistors," in Proc. IRE Int. Conv. Rec., vol. 13, 1966, pp. 27–34.
[22]
D. Serghiou et al., "Terahertz channel propagation phenomena, measurement techniques and modeling for 6G wireless communication applications," IEEE Commun. Surveys Tuts., vol. 24, no. 4, pp. 1957–1996, 4th Quart. 2022.
[23]
R. Agarwal et al., "3D packaging for heterogeneous integration," in Proc. IEEE 72nd Electron. Compon. Technol. Conf. (ECTC), 2022, pp. 1103–1107.