IEEE Solid-States Circuits Magazine - Winter 2022 - 23

technologies, such as advanced
electromechanic technology, material
technology, magnetic tape and
magnetic head, motor servo, and analog
video signal processing circuit technology
incorporated into one system.
Although analog technology was at its
peak, the technological development
aimed at the digitization of video systems
had already quietly started. For
the digitization of these video systems,
appropriate ADCs posed a major
development problem, together with
the digital signal processors (DSPs)
used for image processing.
Figure 1(a) shows a typical videorate
10-bit A/D conversion board that
was available at the time. A monolithic
IC did not exist, and the ADC
board made by Analog Devices. The
board was marketed, but the power
consumption was large at 20 W, and
the price was as much as US$10,000,
which was almost the same price as
a small car. Therefore, for the digitization
of the video equipment, ADC
development was indispensable to
reduce the price and power consumption
such that it could finally be used
for consumer equipment. The need
for fully integrated, low-power ADCs
has shaped my career for many years.
In 1981, we developed an 8-bit flash
ADC [1] using a bipolar process called
low power analog Integrated Circuit
(LOPAC), which was developed to
reduce the cost and power consumption
of VHS analog signal processing
ICs. This ADC was used for electronic
measuring instruments and IC testers
and has been produced for more
than 20 years. In 1982, we developed
a monolithic, integrated, video-rate
10-bit ADC [2], which is displayed in
Figure 1(b). Our ADC was awarded
the 1983 IR100 Award. This ADC contributed
to the development of the
digital video switcher, 256 quadrature
amplitude modulation (QAM)
microwave transmission, early-stage
high-definition TV (HDTV) systems
(MUSE Hi-Vision), and so on. It also
contributed to HDTV relaying for The
1988 Seoul Olympics.
In 1984, we developed an 8-bit
ADC with a conversion speed in
excess of 100 MS/s [3]. This ADC
was used for the MUSE HDTV system's
digital camera, which was
being developed mainly by Japan
Broadcasting Corporation (NHK) For
digitalization of the HDTV's camera
signal, a conversion speed of more
than 75 MS/s was necessary, but
because a high-speed ADC had not
yet been developed, it was difficult
to digitize a high-definition camera
signal. A developed ADC enables the
digitization of high-definition camera
signals. This ADC was also used
for a digital oscilloscope.
In 1989, an HDTV receiver was created
for home use, and several companies
shared and developed the ICs.
Figure 2(a) and (b) presents our developed
Bi-CMOS ADC (AN8130K) [4] and
HDTV receiver board, respectively.
Figure 2(a) illustrates a 10-bit,
35-MS/s, 750-mW Bi-CMOS ADC.
The conversion architecture of a
two-step conversion comprising
interpolation technology by resistance
was invented. Even if there is
an offset voltage mismatch between
conversion stages, better differential
nonlinearity can be realized from
the interpolation. The area was small,
25 mm2, and the cost reduction necessary
for the consumer's TV receiver
was attempted. The patent for interpolation
technology by resistance
won the 1994 Prize for Notable
Inventions. A review of the interpolation
method is given in Matsuzawa's
article " Interpolation Techniques. "
In 1992, we developed a 10-bit,
300-MS/s ADC [5] [see Figure 3(a)] for
more accurate and faster A/D conversions
that support a wider BW and a
higher dynamic range of HDTV signals.
Interpolation circuits using distributed
preamplifiers and resistors
were formed. Although it is a parallel
type, the offset voltage mismatch of
the transistor is effectively relaxed
by approximately eight times. At
(a)
(b)
FIGURE 1: (a) An A/D conversion board (Source: ADI.) and (b) a developed video-rate
10-bit ADC [2].
(a)
(b)
FIGURE 2: (a) A video-rate 10-bit Bi-CMOS ADC [4] and (b) an HDTV receiver board.
IEEE SOLID-STATE CIRCUITS MAGAZINE WINTER 2022
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IEEE Solid-States Circuits Magazine - Winter 2022

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