IEEE Solid-States Circuits Magazine - Spring 2020 - 24

The immense -convenience of these
surveys is evidenced by their citation
metrics on Google Scholar. At the
time of writing, the ADC survey has
had more than 61,000 page views
and been cited more than 270 times,
the smart temperature sensor survey has been cited at least 62 times,
and the PA survey, while newer, has
already been cited 18 times in just
one year.

Since our group at the University
of Calgary is working on low-noise
amplifiers (LNAs), we are naturally
interested in a survey pertaining to
that field. Although LNA surveys
have been conducted for prior publications [4], they are not readily available for download and use by others.
Therefore, we have created such a
survey to fill this gap and provide
other researchers with a convenient,

accessible database of available LNAs
and their features [5]. Our survey
compiles LNAs that have been published in JSSC, TMTT, and MWCL, as
well as in conjunction with ISSCC,
IMS, and RFIC. We invite readers to
review our survey and welcome your
input about entries that may have
been omitted or recorded incorrectly.
Ultimately, however, we welcome you
to use this survey in your own work.

A Few Observations

Noise Figure (dB)

10
8
6
4
2
0
0.1

1
16 nm
45 nm
180 nm
500 nm

10
Frequency (GHz)
22 nm
55 nm
200 nm
Trend

28 nm
65 nm
240 nm

100

32 nm
90 nm
250 nm

40 nm
130 nm
350 nm

FIGURE 1: CMOS LNA noise figure versus center frequency. Trend lines show an apparent
change in the dependence of the noise figure on frequency at below 20 GHz.

Gain (dB)

25
20
15
10
5
0.1

16 nm
45 nm
180 nm
500 nm

10
Frequency (GHz)
22 nm
55 nm
200 nm

28 nm
65 nm
240 nm

100

32 nm
90 nm
250 nm

40 nm
130 nm
350 nm

FIGURE 2: CMOS LNA gain versus center frequency. Although no clear trend is observed
between gain and frequency, newer technologies dominate high-frequency designs.

S P R I N G 2 0 2 0

IEEE SOLID-STATE CIRCUITS MAGAZINE

While many observations can be made
based on our survey, we will focus
on a few trends in CMOS-integrated
LNAs. These trends are identifiable
in the following figures, with newer
technologies shown in blue and older
technologies in green.
In Figure 1, we plot the CMOS LNA
noise figures against the center of
operating frequency bands, f 0. As
can be seen in the distribution of colors, the noise figures appear almost
independent of technology feature
sizes at low frequencies, with newer
technologies exhibiting superior
performance at higher frequencies.
Interestingly, there is a noticeable
change in the dependence of the
noise figure on frequency at slightly
below 20 GHz. We have added two
trend lines to highlight this point. As
LNA designs move to higher frequencies, their designers have to cope with
increased noise and parasitic capacitance. Consequently, we speculate
that common-source LNAs are mostly
used above 20 GHz, where noise is
primarily transistor dominated and
more stages are used to increase gain.
In contrast, transistor noise is low at
lower frequencies, with LNA noise
mostly being affected by passives. We
revisit this in the "Discussion on Figures of Merit" section.
The plot of LNA gain versus center frequency in Figure 2 reveals a
somewhat unexpected but not very
surprising result: LNA gains do not
follow a clear trend with either frequency or technology. The correlation coefficient between gain and
frequency is low, which confirms the
pattern illustrated in the figure. Most

IEEE Solid-States Circuits Magazine - Spring 2020

Table of Contents for the Digital Edition of IEEE Solid-States Circuits Magazine - Spring 2020