IEEE Solid-States Circuits Magazine - Spring 2023 - 72

18dB
21dB
24dB
27dB
30dB
33dB
36dB
39dB
42dB
45dB
BSIM3v3) models in LTspice. The circuit
gain, obtained with an ac analysis,
is shown in Figure 3. The maximum
voltage gain is 43 dB. The upper 3-dB
corner is 33 MHz. The lower corner is
determined by the feedback through
the DCC. The current drawn by this
circuit from a 1.8-V supply is 0.37 mA,
resulting in the power consumption of
0.66 mW. Half of this current is consumed
by the M ,45
gain-boosting cir1MHz
10MHz
Frequency
FIGURE
3: Simulated voltage gain.
100MHz
1GHz
Input
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0
4.44
4.46
4.48
4.50
4.52
4.54
4.56
Time (µs)
FIGURE 4: Simulated transient response.
4.58
4.60
4.62
4.64
4.66
Normalized output
cuit. Other simulations showed that
bandwidths into gigahertz can be
achieved with this circuit, but the contest
transistor parameters and resistor
values limited the power consumption
of this amplifier and its bandwidth.
The simulated input resistance of this
circuit is 1.5 kΩ. For 50 Ω matching, a
higher power consumption than what
is possible with the available components
would be needed. The transient
response to a square-wave input is
shown in Figure 4. The transient behavior
does not exhibit ringing.
Conclusion
This submission to the 2022 SSCS
Student Circuit Contest presents a
high-gain " three-transistor " amplifier,
whose core is based on an uncommon
three-transistor circuit that can
achieve nearly the highest gain out of
56,280 possible functional three-transistor
circuits. To meet the contest criteria,
all available circuit components
are used in this amplifier that achieve
43 dB of gain with a 0.66-mW power
consumption in 0.18-μm CMOS.
25-μA current source. By selecting
Mp3
current of 100+
allows us to further increase g .m2
larger than M ,p4 a large output
μA from the mirror
In
addition, the 0.5-μm length of Mp3
provides high output resistance and
reduces its effect on the amplifier
gain. A transistor Mp2
is used to drive
M3 with a 25-μA current. The Mp2
length is also set to 0.5 μm for high
output resistance. Note that the low
input resistance of the amplifier allows
I2
to flow into M3
without transistors
entering triode. A large Mp5
implements .Cf
Identical, M ,45
together with R3
form a gain-boosting cascode, which
increases the overall gain by 3 dB. In
the final circuit optimization, the three
available resistors were rotated through
possible positions in the circuit to determine
the ultimate configuration.
Circuit Simulation Results
The circuit was simulated using level
49 (Hspice-enhanced version of
Acknowledgment
The author acknowledges the support
of the Natural Sciences and Engineering
Research Council of Canada.
References
[1] D. Shahhosseini et al., " An analog-design
assistant tool and an example of its application, "
in Proc. IEEE Int. Midwest Symp.
Circuits Syst. (MWSCAS), 2013, pp. 233-236,
doi: 10.1109/MWSCAS.2013.6674628.
[2] D. Shahhosseini et al., " Method of generating
unique elementary circuit topologies, "
Can. J. Elect. Comput. Eng., vol. 41, no. 3,
pp. 118-132, Summer 2018, doi: 10.1109/
CJECE.2018.2859621.
72
SPRING 2023
IEEE SOLID-STATE CIRCUITS MAGAZINE
Voltage (mV)
Voltage gain (dB)
http://dx.doi.org/10.1109/CJECE.2018.2859621 http://dx.doi.org/10.1109/CJECE.2018.2859621
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