EMI Camera LSI (EMcam) with 12 x 4 On-Chip
Loop Antenna Matrix in 65-nm CMOS to Measure
EMI Noise Distribution with 60-μm Spatial Precision
Naoki Masunaga, Koichi Ishida, Makoto Takamiya, and Takayasu Sakurai
University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
Abstract- An EMI Camera LSI (EMcam) with a 12 x 4 on-chip
250μm x 50μm loop antenna matrix in 65nm CMOS is developed.
EMcam achieves both the 2D electric scanning and 60μm-levelspatial precision for the first time. The down-conversion
architecture increases the bandwidth of EMcam and enables themeasurement of EMI spectrum. Shared IF block scheme is
proposed to alleviate the increasing power and area penalty
inherent to the matrix measurement. ‘Mixer and antenna selector(MAS)’ reduces the switches and prevents the EMI attenuation
due to the switches. EMI measurement with the smallest 32μm x12μm antenna to date is also demonstrated.

I. INTRODUCTION
An EMI in electronic devices such as cell-phones is
becoming a serious problem because of (1) the increasing
density of the packaging, (2) the increasing number of variousRF transceivers within a electronic device, and (3) theincreasing signal frequency (>1GHz) which result in thedownsizing of the EMI antenna. In order to measure the EMI
noise generated from the fine pattern on PCB or the on-chip
interconnect, 2D EMI distribution measurement with 60μmlevel spatial precision is required. To efficiently andaccurately measure the 2D EMI distribution, the electricscanning instead of the conventional mechanical scanning of
the EMI probe [1] is required. All the conventional
measurement method, however, do not satisfy both the 2D
electric scanning and the 60-μm precision. The spatial
precision of the conventional 2D electric scanning [2-4] ismore than 7.5mm. Though the smallest EMI probe with 50μm
x 22μm is reported [5], the probe is single and used for themechanical scanning.

To solve the problem of the conventional EMI
measurement methods, an EMI camera LSI (EMcam) with thematrix of on-chip loop antennas and measurement circuits isproposed. By using the EMcam, 2D EMI distribution
measurement with 60μm-level spatial precision isdemonstrated for the first time.
II. EMI CAMERA LSI (EMCAM)
Fig. 1 shows an overview and benefits of the proposed
EMcam. By putting the EMcam on top of a DUT LSI, theEMcam measures within-die 2D distributions of EMI noise atvarious frequencies. By clarifying the position and thefrequency of the EMI source, an efficient root cause analysisof the EMI problems is achieved, because the EMI frequency
is an important clue to find the EMI source.
Fig. 2 shows a block diagram of the measurement corecircuit in the EMcam. The EMI noise is picked up by the onchip loop antenna. Then the noise inputs are down-converted,amplified, and low-pass-filtered. While the noise inputs are
just amplified by high-bandwidth amplifiers in [6], the downconversion is very important in our matrix measurement,
because the down-converted noise can be handled with thelow-bandwidth amplifiers consuming low power, which
Pulse generator

Non-overlap clockgenerator (NCG)

On-chip
loop antenna
LObIn

Amplifiers

LO(fLO)IFIFbLOin
Sweep fLO
Cut-off freq=fLPF
OutLPFBiasVoltage

Inb Mixer
Noise inputs(fEMI)

Down-converted noise(fIF=fEMI-fLO)

VOutTime

EMI Camera LSI
On-chip loopantennas

Fig. 2. Block diagram of measurement core circuit in EMcam.
Within-die 2D distribution ofEMI noise at various freq.

PowerInPower

DUT LSI
2 LSI’s
are stacked.

M
eby asEMure
I c d ream su
er ltsaLO

EMIFreq.

Efficient root cause analysis
of EMI problems is achieved.

978-1-4244-5759-5/10/$26.00 ©2010 IEEE

IFLObFreq.

Both position and frequency ofEMI source are clarified.

Fig. 1. Overview and benefits of the proposed EMI camera.

LObLOInb

outoutbIFbin

inb
bias

(a)
(b)
Fig. 3. Circuit schematics. (a) Mixer. (b) Amplifier.

Power
Down-converted
M

M

fLO fEMI Freq.

Sweep fLO
and measureeach VOut

M

M
IF

M
IF

M
IF(e.g.) fLO=15MHz~3GHz, 3-MHz step 0

M
IF

M

M
IF

M

M
IF

M
IF

M
IF

M
IF

Column selector

MAS

MAS
MAS

IF

sel1

sel2

D = 2-to-4 decoder

Comparator
Rectifier
Digital
Out

REF

(a)
sel0

sel1

sel2

sel3

NCG MAS

NCG MAS

NCG MAS

LO
NCG
LOb
LOin

Passivemixer

Proposed mixer
and antenna
selector (MAS)
FabricatedIF block
OutLPFMAS

DMAS

MAS

IFIF

Column selector

MAS = Mixer and antenna selector

IF block
LPF

IF

sel3

LOin
OutMASDMAS

DMAS

MASMAS(a)

MAS

NCG

IF

IF = IF block

DNCG

sel0

IF

M = Mixer

Row decoder

reduces power and increases the bandwidth of EMcam. Fig. 3
shows schematics of the mixer and the amplifier in Fig. 2. The
passive mixer is used to reduce the power. The amplifier is adifferential amplifier with the common mode feedback. Fig. 4
shows a procedure to obtain the EMI noise spectrum using thecircuit in Fig. 2. By sweeping fLO and measuring VOut shownin Fig. 2 at each fLO, the EMI noise spectrum is obtained.
Figs. 5 (a) and (b) show schematics of the straightforward
and proposed measurement circuit array in the EMcam,respectively. 4 measurement units are shown. In order toalleviate the increasing power and area penalty inherent to thematrix measurement, the IF block is shared between 4antennas. Each antenna has the mixer and the non-overlap
clock generator (NCG). The analog signal (Out) is converted
to a digital signal by a rectifier and a comparator. In theNCG

IFFreq.

Fig. 4. Procedure to obtain EMI noise spectrum using the circuit in Fig. 2.

NCG

IFMAS

====

EMI noise spectrum
PowerM
IFMAS

fIF fLPFM
IFMAS0(e.g.) 1MHz 3MHz 999MHz 1GHz

Row decoder

IFMAS

Noise poweris measuredby VOut.

Comparator
Rectifier
REF

DigitalOut(b)Fig. 5. Schematic of (a) straightforward and (b) proposed measurement
circuit array in EMcam.

(b)
Fig. 6. Schematic of (a) straightforward and (b) proposed matrix circuits inEMcam.

straightforward circuit array (Fig. 5(a)), switches are inserted
between the mixer and the IF block. The switches attenuate
the measured EMI noise and the sensitivity of themeasurement circuit is degraded. In contrast, in the proposed
circuit array (Fig. 5(b)), each antenna has the proposed ‘mixer
and antenna selector (MAS)’. When sel0 is high, MAS
operates as the mixer. When sel0 is low, both LO and LOb arelow, and the antenna is separated from the amplifiers. Because
the proposed MAS can operate as both the mixer and antenna
selector, the additional switches in Fig. 5(a) are not required
and the attenuation due to the additional switches is avoided.
Fig. 6 shows a schematic of the straightforward andproposed matrix circuits in the EMcam. In the straightforward
matrix, each antenna has the mixer and the IF block. Incontrast, in the proposed matrix, each antenna has MAS, and 43.5mm1.0mm
Out(a)

Input(a)

12 x 4 antenna matrix

DUT = buffer
Direct input
Input = 30MHz pulse(b)Fig. 7. (a) Chip micrograph. (b) Layout.

LSI
2.5mm
5μm50Ω Top metal30MHz(a)90MHz

LSI50Ω(b)×16 ×32 ×64 ×128(b)Fig. 8. On-chip DUT’s for EMI generation. (a) DUT (wire). (b) DUT(buffer).

antennas share a decoder and the IF block. By sharing thehigh-power IF block, the power and the circuit area are
reduced by 74% and 73%, respectively.

Out power measured by EMI
camera (dBm)×16 ×32 ×64 ×128

320μm
1μm
Top metal

III. EXPERIMENTAL RESULTS-10-15-20-25-30

DUTAntenna

250μm

200300(c)1201008060

DUT = buffer
Down-converted input
Input = 30MHz pulse

402000100100Frequency (MHz)Amplitude of Out (mV)

Amplitude of Out (mV)

DUT = wire
Direct input
Input = 2GHz sine

DUT = buffer
Down-converted input
Input = 30MHz pulse

0The front-end block of the EMcam shown in Fig. 5 (b) was
fabricated in 1.2V, 65nm CMOS process. The chip
micrograph and layout are shown in Fig. 7 and theperformance is summarized in Table I. A 12 x 4 on-chip loop
antenna matrix is embedded and the size of the antenna is
250μm x 50μm. In order to check the performance of theEMcam without using the 2 stacked chips, DUT’s are also
embedded on the same chip. Fig. 8 shows a schematic of the200-50.5

11.5

Power supply voltage of DUT buffer (V)xμm 50μmCalculated⎛ x + 50 ⎞∝ lnln ⎜⎟⎝x⎠(d)Fig. 10. EMI noise of DUT (buffer). (a) Noise waveform. (b) Noisespectrum for reference. (c) Noise spectrum using the EMcam. (d) Measured
dependence of EMcam output on power supply voltage of DUT.

Measured

0050

100150Distance between DUT and antenna (x) (μm)
Fig. 9. Measured and calculated dependence of EMcam output on thedistance between DUT (wire) and antenna.

two DUT’s for EMI generation. In the DUT (wire), a long onchip wire is driven by an off-chip signal generator. The DUT(buffer) emulates clock buffers for global clock distribution.
Fig. 9 shows a measured and calculated dependence of theamplitude of the EMcam output on the distance between theDUT (wire)
260μm

60μm

TABLE I PERFORMANCE SUMMARY.

LSI

DUT = wire
Down-converted inputInput = 1GHz sine

Technology
Supply voltage
GainEMI camera Maximum frequency
LSIFrequency resolution
Dynamic range
Number12 x 4 antenna Matrix
0.1
-0.5
50Ω

-17.9
0.4

-25.9
-26.5

Unit = dBm

On-chip loop Sizeantenna
Antenna pitch

Fig. 11. Within-die 2D distribution of EMI noise measured with the 12 x 4
on-chip antenna matrix.

PowerAmplitude of Out (mV)160
DUT = wire
Direct input
Input = 2GHz sine

140120Core area

100
DUT
Antenna

80
60

Amplifiers
MAS and NCG
Total
Amplifiers
MAS and NCG
Total

65nm CMOS
1.2V
47dB
3.3GHz3MHz33dB
12 x 4 array
250μm x 50μm (array)
32μm x 12μm (single)
60μm (vertical)
260μm (horizontal)
16.06mW
0.16mW
16.22mW
2130μm246μm22176μm2

amplitude of the DUT (wire) input. As the input amplitudedecreases, the output amplitude linearly decreases, whichshows a reasonable operation of the smallest antenna.

32μm

40IV. CONCLUSION

2012μm
2.6μm

00.0

1.0

2.0

3.0

Amplitude of DUT Input (V)Fig. 12. Measured dependence of EMcam output on DUT (wire) input withthe smallest antenna.

DUT (wire) and the antenna. In this measurement, the NCG isturned off and the noise inputs are not down-converted anddirectly measured. The measured results are consistent withthe calculated results, which confirm the validity of theEMcam. The EMI noise generated by the DUT (buffer) isevaluated, because the clock buffer is the main EMI source inan LSI. Figs. 10 (a) and (b) show measured EMI noise
waveform and spectrum of DUT (buffer) using the off-chip
oscilloscope and spectrum analyzer, respectively. The NCG isturned off, similar to Fig. 9. In Fig. 10 (a), the EMI noise
waveform is clearly shown at the rising and falling edge of the30-MHz clock signal. Fig. 10 (c) shows corresponding EMI
noise spectrum measured with the EMcam. In Figs. 10 (b) and(c), the noise peaks match, which confirms the validity of theEMcam. Fig. 10 (d) shows a measured dependence of theamplitude of the EMcam output on the power supply voltageof the DUT (buffer). The amplitude is reduced with thereduced power supply voltage, because the EMI noise
generation is reduced. Fig. 11 shows a within-die 2D
distribution of EMI noise measured with the 12 x 4 on-chiploop antenna matrix of the EMcam. The antenna pitch is 60μm
and 260μm in a vertical and horizontal direction, respectively.
The DUT wire goes across the matrix. As the distance
between the DUT and the antenna increases, the measured
EMI noise decreases.
In order to show the feasibility of the more precise EMcam,
EMI measurement with the smallest size loop antenna (32μmx 12μm) to date is demonstrated. Fig. 12 shows a measured
dependence of the amplitude of the EMcam output on theAn EMI Camera LSI with a 12 x 4 on-chip 250μm x 50μm
loop antenna matrix in 65 nm CMOS is developed. Without
mechanical scanning, within-die 2-D distribution of EMI noise
is measured for the first time at 60-μm-level spatial precision.
The down-conversion architecture increases the bandwidth ofEMcam and enables the measurement of EMI spectrum.
Shared IF block architecture reduced the power and the areaby 74% and 73%, respectively. ‘Mixer and antenna selector(MAS)’ reduces the switches and prevents the EMI
attenuation due to the switches. EMI measurement with thesmallest 32μm x 12μm antenna to date is also demonstrated.
ACKNOWLEDGMENTS
This work is partially supported by METI. The VLSI chips
were fabricated through the chip fabrication program ofVDEC with the collaboration by STARC.
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