IEEE Solid-State Circuits Magazine - Winter 2014 - 25

of the NE5080/81 modem products,
which were featured on the cover of
Vcc
Electronic Design Magazine. Bob was
IQ
R1
R26
175
co-designer with Bob Blauschild who
525
R2
R3
ran the research group. These FSK
500 To 500
modems were used for factory floor
Second
I1
I1
automation in the industrial product
Stage
Q3 Q 4
Q5 Q6
space.
Gain
The Signetics team of Blauschild/
Control
Meyer collaborated on other related
Iref
designs for example the 725MHz
+
R E Q2
Q1 RE
wideband amplifier [3], Figure 1
50
50
in the first Philips oxide-isolated
Vi
-
bipolar process, which was comIX
mercialized in many output power,
bandwidth, and package options
over the years and sold in high
quantities [e.g. NE5205]. Refer to
Figure 3: AGC architecture with extra bleed current to improve noise/distortion tradeoff
Figure 2. The architecture became
(reprinted with permission of the IEEE, authors R.G. Meyer and W.D. Mack [7])
a standard and similar designs were
produced by NEC (e.g. uPC2713T) in
this time frame.
on all types of oscillators and his
Bob Meyer studied the problem of
While making measurements of the
oscillator expertise impacted both
building an amplifier to convert the
NE5205 in an HP s-parameter testset
research as well as the design of
PIN diode photo current to a voltage.
we found peaking in the frequency
many commercial products.
The design called for a trans-impedresponse near the GHz band edge.
Success in the wideband ampliance amplifier (TIA) with 200MHz of
Careful use of tweezers to spread
fier products led customers to ask
bandwidth with good pulse response,
the ground bondwires (while hot in
if we could replace baluns and have
but it needed to withstand a large
the testjig!) eliminated the peak. Bob
programmable gain settings. Bob
variation of input capacitance due to
took 2 seconds to shout out "mutual
took the challenge and drew up a
mounting in hybrids or on PCBs. His
inductance". A quick run upstairs to
new design, based on a variable gain
solution was to avoid the traditional
the SPICE2G manual and a subsequent
architecture with differential inputs
cascode input and Miller compensate
132 column output from SPICE preand outputs. The design, the NE5209,
at the input node [4]. Refer to Figdicted the peaking (SPICE syntax: K1
found application in cellular baseure 4. The products were sold as the
L1 L2 k where k is the coupling coefstations when AGC was needed [7].
NE5212/11/10 with different bandficient between inductors L1 and L2
Refer to Figure 3.
width/noise tradeoffs.
with a value of ~0.3 in our case). From
Around the mid 1980's the potenTo the delight of the designers, the
that day forward we visualized any IC
tial of low cost fiber optic communi5212 part gained numerous designpackage- as a set of coupled induccations for high data-rate applications
ins, and with no competition the selltors. This led to systematic E&M simuspurred tremendous interest in the
ing price was raised each year for
lations of leadframes and bondwires
design of trans-impedance amplifiseveral years! Companion "post-amp"
and with suitable reduction we had a
ers, post amplifiers, and LED or LASER
designs took the output of the TIA and
lumped "package" model- an enabler
drivers to interface with the fiber.
amplified it up to ECL levels. Products
in the design of all GHz prodsuch as the NE5214/17/24/25
ucts to follow.
that Bob architected were
Blauschild and Meyer also
sold as a chip-set with a correVcc(5 V)
designed a wideband classsponding TIA.
170 Ω
0.5 mA
5 kΩ
ImA
B video output driver prodThese chip sets pushed
R3
R1
vO
uct for CRTs [5], and a very
the boundaries of the gain
Q2
Q1
fast 150MHz PLL for Satellite
that could be realized on a
Q3 5 mA
R2
iS
receivers [16]. The PLL featured
CS
single PCB. We saw the prob1.8
kΩ
7.2 kΩ
a precision current controlled
lem when Bob Blauschild
170 Ω R4
R5
oscillator and was commerdetected oscillations on the
cialized to replace expensive
ECL outputs of the 5224 post
hybrids as the NE568. Bob was Figure 4: 5212 TIA architecture (reprinted with permission
amp on a board where it was
very active with grad students of the IEEE, authors R.G. Meyer and R. A. Blauschild [4])
driven by the 5211 preamp.

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