IEEE Solid-States Circuits Magazine - Spring 2023 - 26

to ever-improving health and wellness
for the human race.
References
[1] " Medical electronics market, " Markets and
Markets, Pune, India, 2021. [Online]. Available:
https://www.marketsandmarkets.
com/Market-Reports/medical-electronicsmarket-104528355.html
[2]
J. M. Rabaey, " Human-centric computing, "
IEEE Trans. Very Large Scale Integr. (VLSI)
Syst., vol. 28, no. 1, pp. 3-11, Jan. 2020,
doi: 10.1109/TVLSI.2019.2956529.
Appendix: Related Articles
[A1] D. A. Hall, K. A. A. Makinwa, and T. Jang,
" Quantifying biomedical amplifier efficiency:
The noise efficiency factor, "
IEEE Solid-State Circuits Mag., vol. 15, no. 2,
pp. 28-33, Spring 2023, doi: 10.1109/
MSSC.2023.3256353.
[A2] G. L. Barbruni, D. Ghezzi, and S. Carrara,
" Challenges for miniaturized neurostimulators:
Design of wireless Bio/CMOS
interfaces for brain stimulation, " IEEE
Solid-State Circuits Mag., vol. 15, no. 2, pp.
34-40, Spring 2023, doi: 10.1109/MSSC.
2023.3246004.
[A3] A. Emami and S. Sharma, " 3D localization
of miniaturized devices for precision
medicine: Enabling wireless surgical
navigation, health monitoring, and
targeted drug delivery, " IEEE Solid-State
Circuits Mag., vol. 15, no. 2, pp. 41-48,
Spring 2023, doi: 10.1109/MSSC.
2023.3247686.
[A4] J. Yoo, " Body area network: Connecting
and powering things together around
the human body, " IEEE Solid-State Circuits
Mag., vol. 15, no. 2, pp. 49-58, Spring
2023, doi: 10.1109/MSSC.2023.3264663.
CIRCUIT INTUITIONS (continued from p. 16)
BW Improvement
-10
-20
-30
-40
-50
108
109
SSF
SVF
FVF
References
[1] A. Sheikholeslami, " Voltage follower,
part 1 [Circuit Intuitions], " IEEE SolidState
Circuits Mag., vol. 14, no. 3, pp.
13-15, Summer 2022, doi: 10.1109/MSSC.
2022.3182791.
1010
Frequency (Hz)
FIGURE 5: Frequency responses of the SVF (in blue), FVF (in red), and SSF (in green) showing
the bandwidth (BW) improvement of the FVF and SSF over the SVF.
We wi ll answer these questions
and explore yet another voltage
follower in the next article in
this series.
In summary, we have shown that the
SVF, the FVF, and the SSF all offer the
same voltage gain of around 0.7 V/V.
While the SVF burdens a single transistor
to deliver both the voltage and the
current to the load, the FVF and SSF
divide these two tasks between two
transistors, one delivering the voltage
and one delivering the current. In
doing so, the FVF and the SSF continue
to follow the input voltage even when
they need to supply varying signal currents
to the load. All of this is to say
that the FVF and the SSF have much
lower output resistance compared to
the SVF.
1011
[2] A. Sheikholeslami, " Voltage follower, part
II [Circuit Intuitions], " IEEE Solid-State Circuits
Mag., vol. 15, no. 1, pp. 17-19, Winter
2023, doi: 10.1109/MSSC.2022.3218083.
[3] R. G. Carvajal et al., " The flipped voltage
follower: A useful cell for low-voltage
low-power
circuit design, " IEEE Trans.
Circuits Syst. I, Reg. Papers, vol. 52, no. 7,
pp. 1276-1291, Jul. 2005, doi: 10.1109/
TCSI.2005.851387.
[4] J. Ramirez-Angulo et al., " Comparison of conventional
and new flipped voltage structures
with increased input/output signal swing
and current sourcing/sinking capabilities, "
in Proc. 48th Midwest Symp. Circuits Syst.,
2005, vol. 2, pp. 1151-1154, doi: 10.1109/
MWSCAS.2005.1594310.
[5] P. R. Gray, P. J. Hurst, S. H. Levis, and R. G.
Meyer, Analysis and Design of Analog Integrated
Circuits. New York, NY, USA: Wiley,
2001, p. 213.
[6] A. Sheikholeslami, " Looking into a node
[Circuit Intuitions], " IEEE Solid-State Circuits
Mag., vol. 6, no. 2, pp. 8-10, Spring
2014, doi: 10.1109/MSSC.2014.2315062.
Acknowledgment
Many thanks to Jhoan Salinas from the
University of Toronto for his assistance
with the simulation results in this article.
26
SPRING 2023
IEEE SOLID-STATE CIRCUITS MAGAZINE
Vout/Vin (dB)

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IEEE Solid-States Circuits Magazine - Spring 2023

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