IEEE Solid-States Circuits Magazine - Winter 2021 - 25
2.5
2.4
V (N2_ORIG)
2.35
2.3
2.25
Track 3
(a)
2.5
V (N2_NLA)
(V)
2.45
V (N1_NLA)
2.4
2.35
2.3
2.25
(b)
200
Differential Input: Original
100
(µV)
You didn't see that last one coming,
did you? Well, here's another variation that will catch you off guard. In
Figure 5, we turn M5 into a follower
so that it is not producing any signal gain at all. The gain in this configuration comes from collecting all
of the variable branch currents in
the first stage and the M6 feedback
branch and playing them off against
a fixed current source.
If this is a little hard to get your
head around, you are not alone. It is
not at all apparent that this arrangement is going to work. Don't we have
to know the output impedance-or,
more precisely, the " supply impedance " -of the NLA core to know if
there will be any appreciable gain in
this loop?
It turns out we already have the
answer to this question; we just don't
know it. Figure 6 is the way Paul
Brokaw explains it in a 1986 memo
using bipolar transistors. (The PNPs
with two collectors are exactly that:
single-base, single-emitter, dual collectors. The function is the same
as two transistors wired in parallel
but with isolated collectors.) It is
instructive to follow the logic of Figure 6 because it not only makes the
architecture of Figure 5 more palatable but also gives some insight into
how Paul's creative mind works. Be
warned that this sequence is a bit
like Escher's famous staircase picture [5]: each step seems fine, but,
when you stand back and look at
the overall result, you think, " Whoa,
what just happened? "
■■ Figure 6(a): This is the starting point,
the two-stage amp. (The overall
feedback loop is not shown. This is
just the amp.)
■■ Figure 6(b): A cascode is added to
the output stage.
V (N1_ORIG)
2.45
(V)
This effectively pins the voltage
on N1. The positive feedback loop
(through M6) then works on the bias
of the first stage to move N2 to the
same voltage as N1. Together, the two
mechanisms force Vout = Vin and V(N1)
= V(N2). High-gain heaven!
Differential Input: NLA
0
-100
-200
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3
Input Voltage (Vin)
(c)
FIGURE 3: Comparing the NLA to a conventional two-stage amp. (a) The mirror nodes on a
conventional amp (Figure 1). (b) The mirror nodes on an NLA (Figure 2). (c) The differential
input: Vout - Vin.
VDD
M4 M3
R1
100,000
M6
N1
N2
Vout
Vin
Vin
ac 10
M2
M1
M7
2X
M8
M5
FIGURE 4: The M5 becomes an NMOS transistor but does not have to match M7 or M8.
IEEE SOLID-STATE CIRCUITS MAGAZINE
W I N T E R 2 0 2 1
25
IEEE Solid-States Circuits Magazine - Winter 2021
Table of Contents for the Digital Edition of IEEE Solid-States Circuits Magazine - Winter 2021
Contents
IEEE Solid-States Circuits Magazine - Winter 2021 - Cover1
IEEE Solid-States Circuits Magazine - Winter 2021 - Cover2
IEEE Solid-States Circuits Magazine - Winter 2021 - Contents
IEEE Solid-States Circuits Magazine - Winter 2021 - 2
IEEE Solid-States Circuits Magazine - Winter 2021 - 3
IEEE Solid-States Circuits Magazine - Winter 2021 - 4
IEEE Solid-States Circuits Magazine - Winter 2021 - 5
IEEE Solid-States Circuits Magazine - Winter 2021 - 6
IEEE Solid-States Circuits Magazine - Winter 2021 - 7
IEEE Solid-States Circuits Magazine - Winter 2021 - 8
IEEE Solid-States Circuits Magazine - Winter 2021 - 9
IEEE Solid-States Circuits Magazine - Winter 2021 - 10
IEEE Solid-States Circuits Magazine - Winter 2021 - 11
IEEE Solid-States Circuits Magazine - Winter 2021 - 12
IEEE Solid-States Circuits Magazine - Winter 2021 - 13
IEEE Solid-States Circuits Magazine - Winter 2021 - 14
IEEE Solid-States Circuits Magazine - Winter 2021 - 15
IEEE Solid-States Circuits Magazine - Winter 2021 - 16
IEEE Solid-States Circuits Magazine - Winter 2021 - 17
IEEE Solid-States Circuits Magazine - Winter 2021 - 18
IEEE Solid-States Circuits Magazine - Winter 2021 - 19
IEEE Solid-States Circuits Magazine - Winter 2021 - 20
IEEE Solid-States Circuits Magazine - Winter 2021 - 21
IEEE Solid-States Circuits Magazine - Winter 2021 - 22
IEEE Solid-States Circuits Magazine - Winter 2021 - 23
IEEE Solid-States Circuits Magazine - Winter 2021 - 24
IEEE Solid-States Circuits Magazine - Winter 2021 - 25
IEEE Solid-States Circuits Magazine - Winter 2021 - 26
IEEE Solid-States Circuits Magazine - Winter 2021 - 27
IEEE Solid-States Circuits Magazine - Winter 2021 - 28
IEEE Solid-States Circuits Magazine - Winter 2021 - 29
IEEE Solid-States Circuits Magazine - Winter 2021 - 30
IEEE Solid-States Circuits Magazine - Winter 2021 - 31
IEEE Solid-States Circuits Magazine - Winter 2021 - 32
IEEE Solid-States Circuits Magazine - Winter 2021 - 33
IEEE Solid-States Circuits Magazine - Winter 2021 - 34
IEEE Solid-States Circuits Magazine - Winter 2021 - 35
IEEE Solid-States Circuits Magazine - Winter 2021 - 36
IEEE Solid-States Circuits Magazine - Winter 2021 - 37
IEEE Solid-States Circuits Magazine - Winter 2021 - 38
IEEE Solid-States Circuits Magazine - Winter 2021 - 39
IEEE Solid-States Circuits Magazine - Winter 2021 - 40
IEEE Solid-States Circuits Magazine - Winter 2021 - 41
IEEE Solid-States Circuits Magazine - Winter 2021 - 42
IEEE Solid-States Circuits Magazine - Winter 2021 - 43
IEEE Solid-States Circuits Magazine - Winter 2021 - 44
IEEE Solid-States Circuits Magazine - Winter 2021 - 45
IEEE Solid-States Circuits Magazine - Winter 2021 - 46
IEEE Solid-States Circuits Magazine - Winter 2021 - 47
IEEE Solid-States Circuits Magazine - Winter 2021 - 48
IEEE Solid-States Circuits Magazine - Winter 2021 - 49
IEEE Solid-States Circuits Magazine - Winter 2021 - 50
IEEE Solid-States Circuits Magazine - Winter 2021 - 51
IEEE Solid-States Circuits Magazine - Winter 2021 - 52
IEEE Solid-States Circuits Magazine - Winter 2021 - 53
IEEE Solid-States Circuits Magazine - Winter 2021 - 54
IEEE Solid-States Circuits Magazine - Winter 2021 - 55
IEEE Solid-States Circuits Magazine - Winter 2021 - 56
IEEE Solid-States Circuits Magazine - Winter 2021 - 57
IEEE Solid-States Circuits Magazine - Winter 2021 - 58
IEEE Solid-States Circuits Magazine - Winter 2021 - 59
IEEE Solid-States Circuits Magazine - Winter 2021 - 60
IEEE Solid-States Circuits Magazine - Winter 2021 - 61
IEEE Solid-States Circuits Magazine - Winter 2021 - 62
IEEE Solid-States Circuits Magazine - Winter 2021 - 63
IEEE Solid-States Circuits Magazine - Winter 2021 - 64
IEEE Solid-States Circuits Magazine - Winter 2021 - 65
IEEE Solid-States Circuits Magazine - Winter 2021 - 66
IEEE Solid-States Circuits Magazine - Winter 2021 - 67
IEEE Solid-States Circuits Magazine - Winter 2021 - 68
IEEE Solid-States Circuits Magazine - Winter 2021 - 69
IEEE Solid-States Circuits Magazine - Winter 2021 - 70
IEEE Solid-States Circuits Magazine - Winter 2021 - 71
IEEE Solid-States Circuits Magazine - Winter 2021 - 72
IEEE Solid-States Circuits Magazine - Winter 2021 - 73
IEEE Solid-States Circuits Magazine - Winter 2021 - 74
IEEE Solid-States Circuits Magazine - Winter 2021 - 75
IEEE Solid-States Circuits Magazine - Winter 2021 - 76
IEEE Solid-States Circuits Magazine - Winter 2021 - 77
IEEE Solid-States Circuits Magazine - Winter 2021 - 78
IEEE Solid-States Circuits Magazine - Winter 2021 - 79
IEEE Solid-States Circuits Magazine - Winter 2021 - 80
IEEE Solid-States Circuits Magazine - Winter 2021 - 81
IEEE Solid-States Circuits Magazine - Winter 2021 - 82
IEEE Solid-States Circuits Magazine - Winter 2021 - 83
IEEE Solid-States Circuits Magazine - Winter 2021 - 84
IEEE Solid-States Circuits Magazine - Winter 2021 - 85
IEEE Solid-States Circuits Magazine - Winter 2021 - 86
IEEE Solid-States Circuits Magazine - Winter 2021 - 87
IEEE Solid-States Circuits Magazine - Winter 2021 - 88
IEEE Solid-States Circuits Magazine - Winter 2021 - Cover3
IEEE Solid-States Circuits Magazine - Winter 2021 - Cover4
https://www.nxtbook.com/nxtbooks/ieee/mssc_fall2023
https://www.nxtbook.com/nxtbooks/ieee/mssc_summer2023
https://www.nxtbook.com/nxtbooks/ieee/mssc_spring2023
https://www.nxtbook.com/nxtbooks/ieee/mssc_winter2023
https://www.nxtbook.com/nxtbooks/ieee/mssc_fall2022
https://www.nxtbook.com/nxtbooks/ieee/mssc_summer2022
https://www.nxtbook.com/nxtbooks/ieee/mssc_spring2022
https://www.nxtbook.com/nxtbooks/ieee/mssc_winter2022
https://www.nxtbook.com/nxtbooks/ieee/mssc_fall2021
https://www.nxtbook.com/nxtbooks/ieee/mssc_summer2021
https://www.nxtbook.com/nxtbooks/ieee/mssc_spring2021
https://www.nxtbook.com/nxtbooks/ieee/mssc_winter2021
https://www.nxtbook.com/nxtbooks/ieee/mssc_fall2020
https://www.nxtbook.com/nxtbooks/ieee/mssc_summer2020
https://www.nxtbook.com/nxtbooks/ieee/mssc_spring2020
https://www.nxtbook.com/nxtbooks/ieee/mssc_winter2020
https://www.nxtbook.com/nxtbooks/ieee/mssc_fall2019
https://www.nxtbook.com/nxtbooks/ieee/mssc_summer2019
https://www.nxtbook.com/nxtbooks/ieee/mssc_2019summer
https://www.nxtbook.com/nxtbooks/ieee/mssc_2019winter
https://www.nxtbook.com/nxtbooks/ieee/mssc_2018fall
https://www.nxtbook.com/nxtbooks/ieee/mssc_2018summer
https://www.nxtbook.com/nxtbooks/ieee/mssc_2018spring
https://www.nxtbook.com/nxtbooks/ieee/mssc_2018winter
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_winter2017
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_fall2017
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_summer2017
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_spring2017
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_winter2016
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_fall2016
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_summer2016
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_spring2016
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_winter2015
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_fall2015
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_summer2015
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_spring2015
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_winter2014
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_fall2014
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_summer2014
https://www.nxtbook.com/nxtbooks/ieee/solidstatecircuits_spring2014
https://www.nxtbookmedia.com