Adv. Radio Sci., 4, 21–24, 2006
www.adv-radio-sci.net/4/21/2006/
© Author(s) 2006. This work is licensed
under a Creative Commons License.
Advances in
Radio Science
A varactor tuned low-cost 24 GHz harmonic VCO
M. O. Olbrich, L. Huang, and E. M. Biebl
Fachgebiet Höchstfrequenztechnik, Technische Universität München, 80290 München, Germany
Abstract. We present a low-cost 24 GHz VCO that is based
on a microstrip design combined with discrete packaged devices. The output frequency is generated by a harmonic oscillator. The tunabilty was reached using a varactor diode.
Two versions of the VCO were built, one has a wide tuning
range of 1.1 GHz and the other one has a high output power
of 3.7 dBm.
Our approach to meet the above mentioned requirements is
to integrate microstrip structure design with SMD handling
compatible discrete packaged active devices. Furthermore,
we take advantage of the generally present harmonics in the
transistor of the oscillator. This is common practice to gain
RF output power, generated at moderate frequencies where
low-cost devices are available. The tunabilty was reached
using a varactor diode.
1 Introduction
2
A voltage controlled oscillator is the key component in various microwave systems. Tunability of these VCOs is essential in many systems, e.g. in FMCW radars. Moreover
fabrication variations or temperature drift can easily be compensated by using VCOs.
For the 24 GHz ISM-band an increasing number of applications like automotive radar systems or short-range communication links are proposed. Since the current ISM bandwidth specification limits these applications, the FCC and the
ETSI put significant effort into expanding the specification
for usability for UWB systems. Such systems demand for a
moderate fixed frequency output power of a few mW and an
ultra-wide tuning range to spread the signal. Tuning speed is
also a figure of merit as it directly influences the repetition
rate of the overall system. Finally, the usual prerequisite of
low cost, as well as ease of fabrication is demanded.
Monolithic integrated solutions with a fractional-N-PLL
achieve -6 dBm output power and a tuning range of 500 MHz
(Stelzer et al., 2003). A harmonic DRO was published (Jeon
et al., 1996) with 5.5 dBm output power at 20.5 GHz and a
tuning range of 54 MHz. Another common tuning possibility
is a YIG tuned oscillator. In Khanna and Hauptman (1991)
a YTO is published from 18 GHz to 40 GHz with an output
power of 13 dBm including integrated amplifiers.
Packaged devices are rarely available at 24 GHz due to the
parasitics. And accordingly, low parasitics packages yield
considerably more expensive devices. To bypass this barrier,
a common solution is to generate the oscillation at lower frequencies where adequate devices are available, before mixing the signal to the desired frequency. This can be done by
separate elements, or as shown in our design within one element. Harmonics are present in any oscillator due to the
nonlinearities of the active element. The principle of a harmonic oscillator is to reflect the power at the fundamental
frequency back into the device and to get maximum output
power at the desired harmonic.
The oscillator design is based on the one-port approach.
The transistor circuit has to fulfill the oscillation conditions
Correspondence to: M. O. Olbrich (olbrich@tum.de)
Principle
|0A | · |0P | = 1
(1)
and
6
0A + 6 0P = 2π n, n = 0, 1, 2, ...
(2)
at the fundamental frequency, with the reflection coefficients
|0A |, |0P | of the active and the passive part. According
to Chua et al. (1987) this criterion can be replaced by the
Nyquist plot analysis. The circuit is unstable if the Nyquist
loop (0A · 0P ) encircles the point 1 + j 0 in clockwise direction. The separation plane is set at the source pin of the tran-
Published by Copernicus GmbH on behalf of the URSI Landesausschuss in der Bundesrepublik Deutschland e.V.
ejection of the fundamental freflection coefficient of the active part varies with phase and
O.
et al.:harmonic
A Varactor Tuned
Low-Cost
ofOlbrich
the 1st
is done
by 24 GHz Harmonic VCO
M.O. Olbrich et al.: A Varactor Tuned Low-Cost 24 GHzmagnitude
Harmonic VCOas shown in Fig. 4.
structure.22
M. O. Olbrich et al.: A varactor tuned low-cost 24 GHz harmonic VCO
ock-
ne clockpin
urce
Or thepin
r for the
e the
f the the
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hedrain
VCO optimized for maximum
nd
by
its its
d
by
mpedance
bandpass filter satisfies
-port
wo-port
gs acconditions.
The varactor diode
eters
acee
of
egree
of
ivalent to the passive part. Thus,
h, the diode
the
source
theVCO.
amental
Fig. 1.and
Layout
of the
maximumof
power
ental
Fig.
1.
Layout
of
the
maximum
power
1. Layout of
the maximum
powerVCO
VCO
)as
othastooftotheFig.
varactor
tuned
reflection
hutput
output
art at the fundamental frequency.
ways
to
hetovaractor
diode results mainly
ys
e active
ctive
ase
for a frequency point.
y using
Fig. 3. Layout of the maximum tuning range VCO.
Fig. 3. Layout of the maximum tuning range VCO
3
Design
using
d device
evice
chnolonolocreasing
0001–4,
asing
Therevaractor
herechosen.
actor
or
in the
osen.
n the
as maxpower.
maxe VCO,
ower.
the dedesigns
VCO,
erovided
deg
effort
signs
vided
the
funffort
mplished
network
funntal freshed
done by
work
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aximum
satisfies
or diode
t. Thus,
mum
e of the
sfies
flection
diode
quency.
Thus,
mainly
f the
ction
ency.
ainly
We present two different designs. One, referred to as maximum power VCO, was designed for high output power.
2005
www.atmos-chem-phys.org/acp/0000/0001/
The
other one, referred to as maximum tuning range VCO,
showed a high tuning range. The main difference in the design is the location of the varactor diode. In both designs
the varactor diode is connected to a virtual ground provided
by a λ/4 transformation in order to keep the biasing effort
moderate.
The bias network has to be designed for rejecting the fundamental frequency and the harmonic. This is accomplished
by the combination of two radial stubs in each bias network
Fig. 2.
2. Reflection
Reflection coefficient of the passive part for several
Fig.
several varactor
varactor
as shown in Fig. 1. The rejection of the fundamental frecapacitances (11.9–12.1
(11.9-12.1 GHz)
capacitances
GHz).
quency and the matching of the 1st harmonic is done by
Fig. 2. Reflection coefficient of the passive part for several varactor
means of a microstrip filter structure.
capacitances (11.9-12.1 GHz)
3.2 Maximum tuning range VCO
sistor. The magnitude of 0A is an indicator for the achiev3.1 Maximum power VCO
able
output
power.
The reflection
coefficient
of the the
the maxiactive
Fig.
3
shows
the
layout
of
the
VCO
that
exhibits
3.2 Maximum tuning range VCO
part
influenced
circuit at the gate
and drain
conmumistuning
range.byAthe
parallel-coupled,
strip-line
bandpass
Figure 1 shows the layout of the VCO optimized for maxinectors
of the the
transistor.
Theand
transistor
is modeled
byatitsthe
sfilter
satisfies
oscillation
matching
conditions
mum power output. A stepped impedance bandpass filter satFig. 3 shows the layout of the VCO that exhibits the maxiparameters
by the manufacturer.
Thetogiven
two-port
passive part.given
The varactor
diode is attached
the drain
stub
isfies the oscillation and matching conditions. The varactor
mum
tuning range.
A parallel-coupled,
strip-line
bandpass
s-parameters
were
s-parameters
acof the transistor
at converted
the active into
part.three-port
In this design,
the reflecfilter
satisfies
the oscillation
conditions
atofthe diode is attached to this filter, equivalent to the passive part.
cording
to Khanna
(1985)
toand
gainmatching
additional
degree
tion coefficient
of the
passive
part
isanfixed,
whereas
the reThus, the ground bias supplies both, the diode and the source
passive
Thedesign.
varactor
diode part
is attached
to the
drain
freedom
for the
flectionpart.
coefficient
of the active
varies with
phase
andstub of the transistor. Figure 2 shows a plot of the varactor tuned
ofmagnitude
the transistor
at thein active
In this design, the reflecas shown
Fig. 4. part.
reflection coefficient of the passive part at the fundamental
In addition
to the oscillation
condition at the fundamental
tion
coefficient
of
the
passive
part
is fixed, whereas the re- frequency. Tuning the voltage across the varactor diode refrequency, the matching condition (|0A | = |0P |∗ ) has to be
flection
of thefrequency
active part
fulfilledcoefficient
at the harmonic
to varies
achievewith
highphase
outputand sults mainly in a displacement of the phase for a frequency
magnitude
as
shown
in
Fig.
4.
point.
power.
According to the oscillation criteria there are two ways to
tune the oscillator: Varying either the passive or the active
part. Our tuning approach is to change the phase by using
a varactor diode. The diode is preferable a packaged device
that can be handled with standard SMD fabrication technologies. Since its influence at 24 GHz decreases with increasing
capacitance,
a diode with low capacitance is required. ThereFig. 3. Layout of the maximum tuning range VCO
fore the M/A-COM MA46H120 GaAs hyperabrupt varactor
diode, with a capacitance from 1.1 pF to 0.14 pF is chosen.
Taconic TLP-5-0100 substrate is used. The transistor in the
design
is an Agilent
GaAs PHEMT
www.atmos-chem-phys.org/acp/0000/0001/
Fig.
3. Layout
of the
maximum
tuning ATF-36163.
range VCO
Adv. Radio Sci., 4, 21–24, 2006
www.atmos-chem-phys.org/acp/0000/0001/
3.2
Maximum tuning range VCO
Figure 3 shows the layout of the VCO that exhibits the maximum tuning range. A parallel-coupled, strip-line bandpass
filter satisfies the oscillation and matching conditions at the
passive part. The varactor diode is attached to the drain stub
of the transistor at the active part. In this design, the reflection coefficient of the passive part is fixed, whereas the reflection coefficient of the active part varies with phase and
magnitude as shown in Fig. 4.
www.adv-radio-sci.net/4/21/2006/
Oscillatin
3
Os
M.O. Olbrich et al.: A Varactor Tuned Low-Cost 24 GHz Harmonic VCO
24.4
24.3
sponding
to 0 V and 13 V at the waveform generator output.
24.3
M.
O.
Olbrich
et
al.:
A
varactor
tuned
low-cost
24
GHz
harmonic
VCO
23
The
13
V
in 0a frequency of 24,63
GHz.
M.O. Olbrich et al.: A Varactor Tuned Low-Cost 24 GHz Harmonic VCO result24.2
3
5
10
15
Reverse voltage across the varactor / V
Oscillating frequency
Oscillating/ GHz
frequency / GHz
Fig. 4. Reflection coefficient of the active part for several varactor 24.20
5 at the waveform
10 generator output.
15
sponding to 0 V and 13 V
Reverse voltage across the varactor / V
capacitances (11.5-12.5 GHz)
4. Reflection coefficient of the active part for several varactor
The 13Fig.
V result
in a frequency
of 24,63vs.
GHz.
6. Oscillating
frequency
reverse voltage of the maxi
24.7
citances (11.5-12.5 GHz)
power VCO
Fig. 6. Oscillating frequency vs. reverse voltage of the maximum
24.6
4 Measurements
power VCO
24.7The power variation results from two effects. The ca
24.5
Measurements
itance
variation
of the
varactor
diode changes
not only
All measurement data was taken by a spectrum analyzer.
The power
variation
results
from
two effects.
The capac24.6
phase
at
frequency,
matchin
The modulation
determined
by applying
a variation
24.4
itance
of the
thefundamental
varactor diode
changesbut
notalso
onlythethe
measurement
data wasbandwidth
taken by was
a spectrum
analyzer.
the
passive
part
for
the
harmonic
frequency.
Additionally
rectangular
signal. was
A waveform
generator
provides
phase at the24.5fundamental frequency, but also the matching at
modulation
bandwidth
determined
by applying
a respec24.3
the activefrequency.
part varies
over the tuned
tive
voltages
for two oscillation
to the varactor
the passivemagnitude
part for theofharmonic
Additionally,
the freque
angular
signal.
A waveform
generator frequencies
provides respec24.4
range,
see
Fig.
4.
diode.
is identified
at
magnitude
of the active part varies over the tuned frequency
voltages
for The
two maximum
oscillation modulation
frequenciesbandwidth
to the varactor
24.2
0
5
15
The
frequency10 is approximately
12 GHz.
themaximum
3 dB dropmodulation
of the output
power at a certain
oscillationrange,
fre- see Fig.
Reverse voltage across the varactor / V
4.oscillating
24.3
e. The
bandwidth
identified
Fig. 4. Reflection coefficient
of the activeispart
for severalat
varactor
10
dB
below
the
output
power
of
the
1st
harmonic,
quency
when
increasing
thea modulation
frequency.
The oscillating frequency is approximately 12 GHz. It is see Fi
capacitances
(11.5-12.5
GHz)
3 dB drop
of the
output
power
at
certain oscillation
freFig. 6.
6. Oscillating
Oscillating
frequency vs. reverse voltage of the maximum
Fig.
maximum
24.2
0
5
10 harmonic,15see Fig. 7.
10 dB
below
the output power
of the 1st
ncy when increasing the modulation frequency.
power
VCO.
power
VCO
5
Reverse
voltage across the varactor / V
4.1 Fig.
Maximum
power
VCOof the active part for several
Fig.
4. Reflection
Reflection
4.
coefficient
several varactor
varactor
Measurements
2.5
2
4.1
1.5
4
0.5
0.5
24.3
3
24.3
3.5
2.5
Amplitude / dBm
-40
3.5
1
24.4
24.4
24.5
24.6
Oscillating frequency / GHz
24.5
-5
5
-35
4
Maximum
power VCO
1.5
1
phase at the fundamental frequency, but also the matching at
-5
-10
power
variation
results from
two effects.
The capactheThe
passive
part
for the harmonic
frequency.
Additionally,
the
itance
variation
of
the
varactor
diode
changes
not
only the
-10
magnitude
of the-15active part varies over the tuned frequency
phase
theFig.
fundamental
frequency, but also the matching at
range,atsee
4.
-15
-20 the harmonic frequency. Additionally, the
theThe
passive
part
for
oscillating frequency is approximately 12 GHz. It is
magnitude
of the
the-25
active power
part varies
tuned frequency
-20below
10 dB
output
of theover
1st the
harmonic,
see Fig. 7.
range, see Fig. 4.
-25
-30frequency is approximately 12 GHz. It is
The
oscillating
5
10 dB
the -35
output power of the 1st harmonic, see Fig. 7.
-30below
0
Amplitude
/ dBm / dBm
Amplitude
3
Output power / dBm
Output power / dBm
Output power / dBm
3.5
All measurement
data was taken by a spectrum analyzer.
4
4 modulation
Measurements
The
bandwidth was determined by applying a
rectangular
signal. A waveform generator provides respec3.5
Allvoltages
measurement
data
was taken
by a spectrum
tive
for two
oscillation
frequencies
to the analyzer.
varactor
The
modulation
bandwidth
was
determined
byidentified
applying ata
diode.3 The maximum modulation bandwidth is
rectangular
A waveform
respecthe
3 dB dropsignal.
of the output
power generator
at a certainprovides
oscillation
fretive
voltages
for
two
oscillation
frequencies
to
the
varactor
2.5 when increasing the modulation frequency.
quency
diode. The maximum modulation bandwidth is identified at
the 3Maximum
the output
4.1
VCOpower at a certain oscillation fre2dB drop ofpower
quency when increasing the modulation frequency.
Output power / dBm
4
0
5
Fig.The
6. Oscillating
frequency
vs. reverse
voltage
of theThe
maximum
power variation
results
from two
effects.
capacpower
VCO
itance 0variation of
-5 the varactor diode changes not only the
Amplitude / dBm
4
capacitances (11.5-12.5
(11.5-12.5 GHz).
GHz)
capacitances
Maximum
power VCO
24.6
Oscillating
frequency / GHz
3
24.7
24.7
24.8
-40
0
5
10
0
5
-15
-5
15
20
25
30
35
40
Frequency / GHz
-10
0
10
15
20
25
30
35
40
Frequency / GHz
Fig.
-10
-20 7. Output spectrum of the maximum power VCO
24.8
Fig.
7. Output
spectrum of the maximum power VCO.
Fig. 7.
Output
-15
-25 spectrum of the maximum power VCO
-20
-30
Fig. 5. Output power vs. oscillating frequency of the maximum
Fig. 5.
Output
power vs. oscillating frequency of the maximum
2
4.2 Maximum tuning range VCO
power VCO.
-25
noise
is
-90 dBc/Hz for 1 MHz offset. The modulation band-35
2.5
powerpower
VCO vs. oscillating frequency of the maximum
5. Output
1.5
2
er VCO
4.2 width
Maximum
tuning
VCOshift of 420 MHz, correis-30
2.5 MHz
for range
a frequency
-40 design that showed the maximum tuning range has a
The
0
10
15
25
30
35
40
sponding to
0 V5 and 13
VFrequency
at the 20waveform
generator
output.
/
GHz
-35
1
The
optimized for maximum output power has
range
1.1
Fig.
8. The
reverse
di
4 design
Measurements
Theadesign
that
showed
theGHz,
maximum
tuning
range
has a voltage
tunThe 13ing
V
result
in of
a frequency
ofsee
24,63
GHz.
1.5
-40
peak
power
of
3.7
dBm
and
variations
of
3.2
dB
over
its
tunfrom
the
other
design,
since
it
is
superposed
with
the
d
The
power
variation
results
from
two
effects.
The
capac0
5
10
15
20 The
25 reverse
30
35 voltage
40
he design optimized
for maximum output power has a
ing range
1.1
GHz,
see
Fig.
8.
differs
0.5
Fig. 7. of
Output
spectrum
of Frequency
the
maximum
power
VCO
24.3data was
24.4 taken
24.5by a 24.6
24.7analyzer.
24.8 The
/ GHz
All
measurement
spectrum
1
itance
variation
of
the
varactor
diode
changes
not
only
the
ingofrange
of 580
see Fig.
5. AdB
is the other
bias ofdesign,
the transistor.
output power
from -6.2 d
Oscillating
frequency
/higher
GHz
k power
3.7 dBm
andMHz,
variations
of
3.2
over frequency
its tun- shift
from
since it The
is superposed
withvaries
the drain
modulation bandwidth was determined by applying a rectphase at
the
fundamental
frequency,
but26.5
also GHz,
the matching
at 9. Its p
reached
for
low
varactor
capacitances,
see
Fig.
6.
The
phase
at
25.4
GHz
to
-9
dBm
at
see
Fig.
ange of 580
MHz,0.5signal.
see Fig.
5. A higher
frequency
shift is
bias Fig.
of the
transistor.
Thethe
output
power
varies
from -6.2 dBm
7. Output
spectrum
maximum
power
VCO
angular
A waveform
generator
24.3
24.4
24.5
24.6 provides
24.7the respective
24.8
the passive
part
for
theofharmonic
frequency.
Additionally, the
Fig.
5.
Output
power
vs.
oscillating
frequency
of
maximum
4.2
Maximum
tuning
range
VCO
Oscillating
frequency
/ GHz
noise
is
-90
dBc/Hz
for
1
MHz
offset.
The
modulation
bandnoise
is
-87
dBc/Hz
for
1
MHz
offset.
b
hed for
low
varactor
capacitances,
see
Fig.
6.
The
phase
at
25.4
GHz
to
-9
dBm
at
26.5
GHz,
see
Fig.
9.TheItsmodulation
phase
voltages
for two oscillation frequencies to the varactor diode.
magnitude of the active part varies over the tuned frequency
power
VCO
width
is
2.5
MHz
for
a
frequency
shift
of
420
MHz,
correwidth
is
1.5
MHz
for
a
frequency
shift
of
900
MHz,
co
The maximum
modulation
is identified
at the 3 dBnoiseThe
e is -90 dBc/Hz
for 1 MHz
offset.bandwidth
The modulation
bandis -87seedBc/Hz
for 1the
MHz
offset.tuning
The modulation
bandrange,
Fig.
that 4.
showed
maximum
range has a tunFig. 5.of Output
powerpower
vs. oscillating
frequency
of the frequency
maximum
4.2 design
Maximum
tuning range
VCO
drop
the
output
at maximum
aof
certain
oscillation
h is 2.5 MHz
for
a
frequency
shift
420
MHz,
correwidth
is
1.5
MHz
for
a
frequency
shift
of
900
MHz,
correThe
oscillating
frequency
is
approximately
12
GHz.
It
is
The
design
optimized
for
output
power
has
a
ing
range
of
1.1
GHz,
see
Fig.
8.
The
reverse
voltage
differs
power VCO
whenpower
increasing
modulation
frequency.
peak
of 3.7the
dBm
and variations
of 3.2 dB over its tun-
www.atmos-chem-phys.org/acp/0000/0001/
ing range
of 580optimized
MHz, see for
Fig.maximum
5. A higher
frequency
The design
output
powershift
has isa
4.1 Maximum
power VCO
w.atmos-chem-phys.org/acp/0000/0001/
reached
for low
varactor
capacitances,
Fig.
Theitsphase
peak power
of 3.7
dBm and
variations see
of 3.2
dB6.over
tunnoise
is -90ofdBc/Hz
for 1see
MHz
The modulation
banding range
580 MHz,
Fig.offset.
5. A higher
frequency shift
is
The design
optimized
maximumshift
output
power
has a peak
width
is 2.5
for afor
frequency
of Fig.
420
MHz,
reached
for MHz
low varactor
capacitances,
see
6.
The correphase
power of 3.7 dBm and variations of 3.2 dB over its tuning
noise is -90 dBc/Hz for 1 MHz offset. The modulation bandrange of 580 MHz, see Fig. 5. A higher frequency shift is
width is 2.5 MHz for a frequency shift of 420 MHz, correwww.atmos-chem-phys.org/acp/0000/0001/
reached for low varactor capacitances, see Fig. 6. The phase
www.atmos-chem-phys.org/acp/0000/0001/
www.adv-radio-sci.net/4/21/2006/
10 dB
below
theshowed
output the
power
1st harmonic,
see
7.
from
the
other
design,
since
itofisthe
superposed
withhas
theaFig.
drain
The
design
that
maximum
range
tunAtmos. tuning
Chem.
Phys.,
0000,
0001–4, 2
biasrange
of theoftransistor.
variesvoltage
from -6.2
dBm
ing
1.1 GHz,The
see output
Fig. 8. power
The reverse
differs
4.225.4
Maximum
tuning
range
Atmos.
Phys.,
at
GHz
-9
dBmsince
atChem.
26.5
see0000,
Fig.
9.0001–4,
Its drain
phase2005
from
the
othertodesign,
itVCO
isGHz,
superposed
with
the
noiseofisthe
-87transistor.
dBc/Hz for
MHz offset.
The modulation
bandbias
The1output
power varies
from -6.2 dBm
The design
showed
maximum
tuning
range
has correa tunwidth
1.5that
MHz
for a the
frequency
shift
900
at
25.4isGHz
to -9 dBm
at
26.5 GHz,
seeofFig.
9.MHz,
Its phase
ing range of 1.1 GHz, see Fig. 8. The reverse voltage differs
noise is -87 dBc/Hz for 1 MHz offset. The modulation bandfrom the other design, since it is superposed with the drain
width is 1.5 MHz for a frequency shift of 900 MHz, correAtmos.
Chem.power
Phys.,varies
0000,from
0001–4,
2005
bias of the transistor.
The output
-6.2 dBm
Atmos. Chem. Phys., 0000, 0001–4, 2005
Adv. Radio Sci., 4, 21–24, 2006
M.O. Olbrich et al.: A Varactor Tuned Low-Cost 24 GHz Harmonic VCO
The416 V result in a frequency of 26,44 GHz.
ding to 3 V and 16 V at the waveform generator output.
26.6 to 3 V and 16 V at the waveform generator output.
-5
16 V resultsponding
24in a frequency of 26,44 GHz.
M. O. Olbrich et al.: A varactor tuned low-cost 24 GHz harmonic VCO
26
25.8
-5
26.2
26.4
26
26.2
25.8 26
25.625.8
25.6
25.4
-5
25.6
0
25.4
-5
5
10
15
20
25
Reverse Voltage / V
0
5
10
15
20
25
Reverse Voltage / V
25.4
-5
Fig. 8. 0Oscillating
frequency
vs.15 varactor
5
10
20 voltage
25 of the maximum
Reversefrequency
Voltage / vs.
V varactor voltage of
tuning
VCO
Fig.range
8. Oscillating
Oscillating
Fig.
8.
of the
the maximum
maximum
tuning range
range VCO
VCO.
tuning
8. Oscillating frequency vs. varactor voltage of the maximum
−6
g range VCO
−6
-10
-10
-15
-15
-20
-15
-5
-20
-25
-25
-30
Amplitude / dBm
26.2
26.6
Amplitude / dBm
26.4
-10
26.4
Amplitude / dBm
Oscillating Frequency / GHz
26.6
Oscillating Frequency / GHz
Oscillating Frequency / GHz
The 16 V result in a frequency of 26,44 GHz.
-25
-30
-35
-40
-30
-35
-20
-35
-45
-40
-40
-45
-45
-50
-50
0
5
10
15
20
25
30
35
40
Frequency / GHz
0
5
10
15
20
25
30
35
40
Frequency / GHz
-50
Fig.
of
maximum
tuning
range
VCO
0 10.5 Output
10 spectrum
15
20 the 25
30
35
40
Frequency
/ GHz
Fig. 10. Output spectrum of
the maximum
tuning range VCO
Fig.Output
10.
spectrumofofthe
the maximum
maximum tuning
range
VCO.
Fig. 10.
spectrum
tuning
range
VCO
5 Output
Conclusions
5 Conclusions
−6.5
We have presented two versions of a 24 GHz varactor tune
5WeConclusions
have presented two versions of a 24 GHz varactor tuned
harmonic
One exhibits
a high
tuning
range
5 Conclusions
−7
harmonic
VCO.VCO.
One exhibits
a high tuning
range
of 1.1
GHzof 1.1 GH
−6
We
have
presented
two
versions
of
a
24
GHz
varactor
tuned
and
an
output
power
of
-6
dBm.
The
other
onea exhibits
and an output power of -6 dBm. The other one exhibits
−7.5−7.5
−6.5
harmonic
VCO.
One
exhibits
a
high
tuning
range
of
1.1
GHz
We have
presented
two
versions
of
a
24
GHz
varactor
tuned powe
lower
tuning
range
of
580
MHz
with
a
higher
output
lower tuning range of 580 MHz with a higher output power
−8 −8
and
an
output
power
of
-6
dBm.
The
other
one
exhibits
of 3.7
dBm.
For
application
as a tuning
synthesizer
in aofFMCW
−7
ofVCO.
3.7 dBm.
For
the application
as arange
synthesizer
in a FMCW
harmonic
Onetheexhibits
a high
1.1aGHz
lower
tuning
range
of
580
MHz
with
a
higher
output
power
−8.5−8.5
radar,
the required
linearity
of the voltage
across
theacross
varactor
radar,
the
required
linearity
of
the
voltage
the avaracto
and
an
output
power
of
-6
dBm.
The
other
one
exhibits
−7.5
of
3.7 dBm.
Foroutput
the application
ascan
a synthesizer
in by
a FMCW
−9
diode
and
the
frequency
be
achieved
using
a
−9
diode
and the
output
can bethe
achieved
by using
lowerradar,
tuning
range
oflinearity
580
MHz
a higher
output
power
the required
of frequency
thewith
voltage
across
varactor
−8
compensation
network.
−9.5
compensation
network.
of
3.7
dBm.
For
the
application
as
a
synthesizer
in
a
FMCW
−9.5
diode
the outputof
frequency
canrange
be achieved
by using by
a
An and
enhancement
the tuning
can be achieved
−8.5
−10
An
enhancement
of
the
tuning
range
can
be
achieved b
compensation
network.
radar,
the
required
linearity
of
the
voltage
across
the
varactor
tuning the active and the passive part, analogical the match−10
−10.5
Ancan
enhancement
ofkeep
the
tuning
range
can
be
achieved
by thea match
tuning
the active
and
passive
part,
analogical
−9
diodeing
and
the
output
frequency
can
be
achieved
by using
25.4
25.6
25.8
26
26.2
26.4
26.6
be aligned
to
thethe
output
power
more
constant.
−10.5
Oscillating
Frequency
/ 26.2
GHz
tuning
thecan
active
and the passive
part,
analogical
the match25.4
25.6
25.8
26
26.4
26.6
ing
be
aligned
to
keep
the
output
power
more
constant.
compensation network.
−9.5
Oscillating Frequency / GHz
ing can be aligned to keep the output power more constant.
enhancement of the tuning range can be achieved by
Fig. 9. Output power vs. oscillating frequency of the maximum AnReferences
−10
Fig.
9.
Output
power
vs.
oscillating
frequency
of
the
maximum
tuning
active and the passive part, analogical the matchtuning
range
VCO
Fig. 9. Output power vs. oscillating frequency of the maximum the
References
−10.5
tuning
range
VCO.
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A., Höftenberger,
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25.8
26
26.2
26.4
26.6
ing can be aligned
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