ETC P14827EJ1V0AN00

Application Note
RF/IF Down-Converter + PLL Frequency
Synthesizer ICs for GPS Receivers
Usage and Applications of µPB1005K
Document No. P14827EJ1V0AN00 (1st edition)
Date Published September 2000 N CP(K)
©
2000
Printed in Japan
[MEMO]
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Application Note P14827EJ1V0AN00
NESAT (NEC Silicon Advanced Technology) is a trademark of NEC Corporation.
The information in this document may be revised without notice.
This document introduces general applications of the products in this series. The application circuits and
circuit constants in this document are not intended for use in actual mass production design. In addition, please
take note that restrictions of the application circuit or standardization of the application circuit characteristics are
not intended.
Especially, characteristics of high-frequency ICs change depending on the external components and
mounting pattern. Therefore the external circuit constants should be determined based on the required
characteristics on your planned system referring to this document and characteristics should be checked before
using these ICs.
• The information in this document is current as of September, 2000. The information is subject to
change without notice. For actual design-in, refer to the latest publications of NEC's data sheets or
data books, etc., for the most up-to-date specifications of NEC semiconductor products. Not all
products and/or types are available in every country. Please check with an NEC sales representative
for availability and additional information.
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developed based on a customer-designated "quality assurance program" for a specific application. The
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Customers must check the quality grade of each semiconductor product before using it in a particular
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The quality grade of NEC semiconductor products is "Standard" unless otherwise expressly specified in NEC's
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(Note)
(1) "NEC" as used in this statement means NEC Corporation and also includes its majority-owned subsidiaries.
(2) "NEC semiconductor products" means any semiconductor product developed or manufactured by or for
NEC (as defined above).
M8E 00. 4
Application Note P14827EJ1V0AN00
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[MEMO]
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Application Note P14827EJ1V0AN00
CONTENTS
1. INTRODUCTION............................................................................................................................... 6
2. PRODUCT CONCEPT ...................................................................................................................... 6
3. PRODUCT FEATURES .................................................................................................................... 7
3.1 Main Features ......................................................................................................................... 7
3.2 Package ................................................................................................................................... 9
4. APPLICATION DESIGN EXAMPLES ............................................................................................ 10
4.1 Application design examples.............................................................................................. 10
4.2 External Component Examples .......................................................................................... 13
4.3 RF Matching Circuit and RF Filter Characteristics ........................................................... 14
4.4 VCO Design........................................................................................................................... 16
4.5 Temperature Dependence of VCO Characteristics ........................................................... 17
4.6 Loop Filter Design................................................................................................................ 18
5. PLL CHARACTERISTICS .............................................................................................................. 20
5.1 Standard Spectrum Waveform and C/N Characteristics .................................................. 20
5.2 Lockup Time Characteristics .............................................................................................. 21
5.3 2nd IF Output Spectrum Characteristics ........................................................................... 21
6. CONCLUSION ................................................................................................................................ 23
APPENDIX
(1) Smith charts for input/output ports.................................................................................... 24
(2) External filter example and characteristics ....................................................................... 25
(3) Related documents .............................................................................................................. 27
CAUTIONS
(1)
Observe precautions for handling because this device, which employs an ultra-fine process, is very sensitive to
electrostatic discharges.
(2)
The bypass capacitor should be attached to the VCC pin.
(3)
Design the loop filter constant according to the VCO to be used.
(4)
Form the ground pattern as wide as possible.
(5)
Insert a DC cut capacitor for high-frequency signal I/O pins.
(6)
When soldering, leave the bias in the OFF status unless evaluating the VCO.
Application Note P14827EJ1V0AN00
5
1.
INTRODUCTION
The Global Positioning System (GPS) was first developed in the United States and is now also widely used in
civilian applications all over the world. GPS receivers are used as position information receivers such as those in car
navigation systems, and the market for such receivers is rapidly expanding throughout the world, including Japan.
This market expansion is resulting in lower prices for GPS modules, which has effectively broadened their application
scope to include systems such as notebook computers and wristwatch-size miniature portable receivers. Rising
market needs for portable systems that include GPS modules have boosted demand for GPS-related ICs that are
lower priced, consume less power, and come in compact packages that enable high-density mounting.
NEC already sells the µPC2756T/TB and the µPC2753GR frequency down-converters for GPS receivers. To meet
the needs cited above, NEC has also been developing and commercializing new ICs that integrates a PLL frequency
synthesizer and frequency down-converter on the same chip.
2.
PRODUCT CONCEPT
The µPB1005K is a high-frequency silicon monolithic IC developed for frequency converters used in GPS
receivers. This IC integrates on a single chip a frequency converter (down-converter) with an operating frequency
band corresponding to the civilian GPS frequency (L1 frequency = 1575.42 MHz) and a PLL synthesizer that
stabilizes the receiving frequency. This IC uses NEC’s own NESATTM (NEC Silicon Advanced Technology) III ultrafine fabrication process for 0.6 µm emitter width. The fact that the only frequency for civilian GPS is L1 enables the
use of a fixed-frequency division method that eliminates input of frequency data or switching of frequency division
values, which are required in conventional PLL frequency synthesizers. The reference frequency of 16.368 MHz is
provided in accordance with the input frequency specification for demodulation ICs, which are currently the dominant
type. This IC comes in a 36-pin plastic QFN package that enables high-density integration of chip sets.
6
Application Note P14827EJ1V0AN00
3.
PRODUCT FEATURES
3.1 Main Features
The main features of this new product are summarized below.
(1)
Double conversion method:
Enables use of dielectric RF filter.
(2)
High integration of RF block:
Single-chip integration of RF/IF down-converter and PLL
frequency synthesizer
(3)
Enables high density and
surface mounting:
36-pin plastic QFN package
(4)
Eliminates channel selection frequency data: Uses fixed frequency division with lockup activated at power-on.
(5)
Large phase comparison frequency:
The reference spurious signal output does not appear in the
(6)
Enables effective use of external filter:
Accepts a higher frequency for 1st IF, which makes it easier to
vicinity of the VCO carrier, which facilitates loop filter design.
reduce spurious emissions due to insertion of LC filters for the 1st
and 2nd IF.
(7)
2nd IF output by clipped wave:
An on-chip differential 2nd IF amplifier provides a limiter effect.
(8)
Gain adjustment enabled in IF mixer:
When necessary, an external control circuit can be connected to
(9)
Reference frequency:
16.368 MHz
enable auto gain control.
(10) Power supply voltage VCC = 2.7 to 3.3 V:
Applicable for portable GPS receivers.
Table 3-1 provides a product overview, and Figure 3-1 show the product’s pin configuration and internal block
diagram. See the data sheet for the product specifications.
Table 3-1. Product Overview
Parameter
µPB1005K
Reference frequency
16.368 MHz
2nd IF frequency
4.092 MHz
Receiving frequency
1 575.42 MHz
Power supply voltage
2.7 to 3.3 V
Power consumption
Package
45.0 mA
36-pin plastic QFN
Application Note P14827EJ1V0AN00
7
GND
(2ndIF-AMP)
2ndIFin1
2ndIFin2
2ndIFbypass
VCC
(2ndIF-AMP)
2ndIFout
N.C.
REFout
VCC
(Reference block)
Figure 3-1. µPB1005K Pin Configuration and Internal Block Diagram
27
26
25
24
23
22
21
20
19
IF-MIXout 28
18 N.C.
N.C. 29
17 REFin
VGC
(IF-MIX) 30
16 N.C.
2
GND
15 (Divider block)
VCC
(IF-MIX) 31
8
N.C. 32
14 LOout
25
IF-MIXin 33
PD
GND
(IF-MIX) 34
8
VCC
13 (Divider
block)
12 GND
(Phase detector)
4
5
6
7
8
9
VCC
(Phase detector)
N.C.
PD-Vout3
3
GND
(1stLO-OSC)
2
1stLO-OSC2
1
1stLO-OSC1
10 PD-Vout2
VCC
(1stLO-OSC)
VCC
(RF-MIX) 36
GND
(RF-MIXin)
11 PD-Vout1
RF-MIXin
RF-MIXout 35
Application Note P14827EJ1V0AN00
3.2 Package
The µPB1005K uses a non-lead 36-pin QFP (QFN) package. The pins located at the four corners of the 36-pin
QFN package (pins 9-10, pins 18-19, pins 27-28, and pins 36-1) are called island pins. They are provided to fix the
lead frame and do not serve any other function, thus they do not get connected inside the chip.
These island pins are thinner than the other function pins. They are not to be soldered, but in order to avoid
contact between brace pins and other pins, trace a pattern and leave the brace pins unconnected.
Figure 3-2. 36-Pin Plastic QFN (Unit: mm)
6.2 ± 0.2
6.2 ± 0.2
6.0 ± 0.2
6.0 ± 0.2
6.2 ± 0.2
6.0 ± 0.2
4 – C0.5
Pin 36
Pin 1
6.2 ± 0.2
6.0 ± 0.2
0.6 ± 0.1
1.0 MAX.
0.22 ± 0.05
0.5 ± 0.025
Back side of product
Application Note P14827EJ1V0AN00
9
4.
APPLICATION DESIGN EXAMPLES
4.1 Application design examples
Figure 4-1 show a circuit example of a GPS frequency converter block that was designed using an application
evaluation board for this IC. Figure 4-2 shows examples of implemented patterns. This application evaluation board
is a PCB used to evaluate frequency converter blocks for GPS receivers that include the µPB1005K, and the board
has printed patterns that enable mounting of external ICs, filters, to TCXO.
Figure 4-1. Application Circuit Example
VCC (3 V)
1 000
pF
0.1 µ F
10 000 1 000
pF
pF
1 000 pF
REFout
0.1 µ F
1 000 pF
2nd IF filter
27
0.01 µ F
1 000 pF
VGC
26
25
24
23
22
21
20
19
28
18
29
17
30
16
2
31
1 µF
1 000 pF
8
32
1 000 pF
1 000 pF
14
25
13
LOout
1 000 pF
1 000 pF
PD
1st LO
monitor
1 000 pF
TCXO
1 000 pF
15
33
1st IF filter
2nd IFout
1.95 kΩ
34
12
35
11
36
10
1 000 pF
RFin
RF amplifer
1 000 pF
1 000 pF
RF filter
1 000 pF
6.8
nH
1
2
3
4
24
pF
1 pF
5
6
7
8
9
1.2 kΩ
24
pF
6.2 kΩ
33 nF
4.7 kΩ
4.7 kΩ
3.9 nH
1 000 pF
1 800 pF
The application evaluation board shown in Figure 4-2 has printed patterns for monitoring the following items, in
addition to the application’s input/output operations.
<1>
1st LO monitor: Monitoring is enabled by coupling a capacitor to pin 35 (1st IF output pin of RF mixer). This
can be used to monitor the oscillation frequency when adjusting the external circuit
constant of the 1st LO. It can also be used to monitor image leakage, the 1st IF frequency,
as well as 2nd LO leakage to the 1st IF.
<2>
Loout:
<3>
1st LO ex-in:
This enables monitoring of the phase comparison frequency.
This can be used when evaluating external input from a signal generator without
configuring a VCO using a PLL.
10
Application Note P14827EJ1V0AN00
Figure 4-2. Application Evaluation Board Implementation Example
(a) Top view
70 mm
NEC
1st LO
monitor
C7
2nd
IF
filter
C10
C9
2nd
IF
out
C8
50 mm
C11
TCXO
out
µ PB1005K
C12
RF in
C13
R3
R4
C4
R2
C3
R1
C5
C6
C1
L1
C2
µ PB1005K
1st LO
ex-in
LO out
3 mm
20 mm
Application Note P14827EJ1V0AN00
11
(b) Bottom view
C
18
C C
19 20
C17
1st
IF
filter
µ PC
2749
C
C21 22
C
16
C
15
L2
C25
C
14
V-D R5
TCXO
12
Application Note P14827EJ1V0AN00
RF
filter
C23
C24
Table 4-1. Ratings for External Capacitors and Resistors
Component Type
Symbol
Rating
C1
1 pF
C2, C5, C6, C10, C12, C13, C16 to C19, C21 to C25
1 000 pF
C3
1 800 pF
C4
33 nF
C7, C8
0.1 µF
C9
0.01 µF
C11
1 µF
C14, C15
24 pF (UJ)
C20
10 000 pF
L1
6.8 nH
L2
3.9 nH
R1
6.2 kΩ
R2, R5
4.7 kΩ
R3
1.2 kΩ
R4
0Ω
Chip capacitor
Chip inductor
Chip resistor
The chip capacitor and chip resistor manufactured by Murata Manufacturing Co., Ltd. are used.
4.2 External Component Examples
Table 4-2 lists external components other than capacitors, inductors, and resistors. These types of commercial
components can be used. The following components and manufacturers are listed only as examples, so any
components whose characteristics are similar to the listed components can be used.
Table 4-2. External Component Examples
Component
Type
Part number
Manufacturer
RF amplifier
SiMMIC
µPC2749TB
NEC
RF filter
Dielectric BPF
Type TDF, TDF3A-1575B-10
Toko
1st IF filter
BPF for LC
Type 5CCEW, 662BBX-037
Toko
2nd IF filter
LPF for LC
Type FST, 630LKN-1006
Toko
Inductor for VCO
Layer-built chip L
LL1608-F3N9S (3.9 nH)
Toko
V-Di
Varactor diode
1SV285
Toshiba
TC7S04F, etc.
Toshiba
TCXO-201C1 (16.368 MHz)
Kinseki
Output buffer
Reference signal oscillator
Caution
TCXO
The external components and their characteristics are presented in summary form. For details
concerning these external components, including these filters, contact the respective manufacturers.
Application Note P14827EJ1V0AN00
13
4.3 RF Matching Circuit and RF Filter Characteristics
In dielectric RF filters and other filters, 50 Ω impedance is connected to inputs and outputs to regulate insertion
loss and attenuation characteristics. Figure 4-3 illustrates an RF filter’s S11 characteristics when ZL = 50 Ω and when
ZL ≠ 50 Ω. As shown in the figure, this RF filter is best suited for applications in which ZS = ZL = 50 Ω.
Figure 4-3. S11 of RF Filter
(a) When ZL = 50 Ω
S11
REF
1
log MAG.
S11
REF 0.0 dB
10.0 dB/
1
−20.731 dB
1.0 Units
200.0 m Units/
42.783 Ω 4.3164 Ω
CENTER
1.57542 GHz
MARKER 1
1.57542 GHz
1
START
STOP
1.075420000 GHz
2.075420000 GHz
START
STOP
1.075420000 GHz
2.075420000 GHz
(b) When ZL = 100 Ω
log MAG.
S11
REF 0.0 dB
10.0 dB/
1
−8.5229 dB
S11
REF 1.0 Units
1
200.0 m Units/
74.668 Ω −42.637 Ω
CENTER
1.57542 GHz
MARKER 1
1.57542 GHz
1
START 1.075420000 GHz
STOP 2.075420000 GHz
14
START 1.075420000 GHz
STOP 2.075420000 GHz
Application Note P14827EJ1V0AN00
The µPC2749TB can be used at the front stage of the RF filter as an internal 50 Ω matching RF amplifier, and the
RF input pin that becomes the RF filter load should be configured with a matching circuit that includes a DC cut
capacitor, an external series inductor, and an external parallel capacitor. Figure 4-4 illustrates the S11 characteristics
of the RF input pin. As shown in this figure, this makes matching relatively simple.
Since the RF filter is inserted between the RF mixer input pin and the front-stage RF amplifier, it is useful for image
level suppression.
Figure 4-4. S11 Characteristics for 50 Ω Impedance Matching at RF Input Pin
Monitor (RF filter output mount section)
6.8 nH
<1>
Connector
1 pF
S11
REF 1.0 Units
1
200.0 mUnits/
49.246 Ω −4.7383 Ω
log MAG.
S11
REF 0.0 dB
10.0 dB/
1
−25.737 dB
MARKER 1
1.57542 GHz
MARKER 1
1.57542 GHz
1
1
START 1.075420000 GHz
STOP 2.075420000 GHz
START 1.075420000 GHz
STOP 2.075420000 GHz
Application Note P14827EJ1V0AN00
15
4.4 VCO Design
Basic design
Since the base pins of the differential amplifier type oscillator protrude, obtain the oscillation by cutting off the DC
flow and allowing positive feedback through the varactor diode and the inductor. Use a varactor diode that has a
small minimum capacitance, such as Toshiba’s 1SV285. The VCO control voltage should be applied via a resistor
with a resistance of 4.7 kΩ, for example. Determine the relation between the VCO control voltage and the oscillation
frequency based on the varactor diode’s variable capacitance value and the inductor’s value. In NEC’s application
evaluation, L = 3.9 nH because the VCO oscillation frequency is 1636.80 MHz.
Verification after mounting on PCB
When it is not possible to verify the parasitic parameter effect of the PCB only by theoretical VCO design, we
suggest comparing theoretical design with PCB evaluation results in the manner described below.
While monitoring local leakage via a spectrum analyzer that has been connected to the 1st LO monitor, apply a 1.5
V control voltage to VCO. Next, adjust the inductor’s value or the mounting position. Lockup is enabled when the
inductor’s value comes to match the 1st LO frequency’s TYP value. Figure 4-5 illustrates the VCO sensitivity
characteristics and shows a circuit diagram.
Figure 4-5. VCO Sensitivity Characteristics Example and Circuit Diagram
3.5
Control voltage VCONT (V)
3.0
2.5
2.0
1.5
1.0
0.5
0
0
1.50
1.55
1.60
1.65
1.70
1.75
VCO oscillation frequency for 1st LO fVCO (GHz)
VCC
Internal (to IC)
3
VCC
To RF-MIX or
prescaler input
amplifier
External
DC cut
4
L
Control voltage
(from PLL loop filter)
5
DC cut
6
16
Application Note P14827EJ1V0AN00
4.5 Temperature Dependence of VCO Characteristics
Configure the VCO so as to minimize frequency fluctuations caused by the ambient temperature. If the VCO
frequency reaches a range that disables PLL operations of this IC due to the ambient temperature fluctuation by the
external components temperature coefficient, lockup operation becomes impossible.
Figures 4-6 and 4-7 show the dependence on ambient temperature of VCO sensitivity characteristics when using
the CH standard, which uses a small rate of change in temperature compensation, and UJ standard, which uses a
large rate of change in temperature compensation, for the DC cut capacitor of the base pin of the differential amplifier
type oscillator, respectively. Using a UJ standard capacitor is particularly effective for suppressing frequency
fluctuations at low temperatures.
Also, since the slope of the VCO sensitivity curve is determined by the varactor diode, use a varactor diode with
small frequency fluctuation characteristics within the VCO control voltage range (0 to 3.0 V).
Figure 4-6. VCO Sensitivity Characteristics when
Figure 4-7. VCO Sensitivity Characteristics when
Using UJ Standard for DC Cut Capacitor
3.5
3.5
3.0
3.0
2.5
TA = +85 ˚C
2.0
1.5
TA = +25 ˚C
1.0
0.5
Control voltage VCONT (V)
Control voltage VCONT (V)
Using CH Standard for DC Cut Capacitor
2.5
TA = +85 ˚C
2.0
1.5
TA = +25 ˚C
1.0
0.5
TA = −40 ˚C
0
TA = −40 ˚C
0
0
1.50
1.55
1.60
1.65
1.70
1.75
VCO oscillation frequency for 1st LO fVCO (GHz)
0
1.50
1.55
1.60
1.65
1.70
1.75
VCO oscillation frequency for 1st LO fVCO (GHz)
Application Note P14827EJ1V0AN00
17
4.6 Loop Filter Design
Adjust the loop filter constant until the carrier’s C/N drops below −40 dBc at 12.5 kHz detuning. Note that there is a
relation between the loop filter constant and the VCO sensitivity characteristics. The parameters and corresponding
relational expressions required for designing the loop filter are shown below (persons wishing to study these
parameters and relevant logic should see the existing PLL documentation.)
Parameters required for design of loop filter
•
PLL block parameters: Phase comparator gain Kφ, VCO gain KV, dividing ratio N
•
PLL loop parameters: Damping filter ζ, natural angular frequency ωn
Relational expressions for active lag-lead filter
CC
Kφ • KV
R1 =
N • ω2n • C
R2 =
CC =
2•ζ
ωn•C
(Ω)
R2
Phase/frequency
comparator output
(Ω)
1
R2 • (5 to 10) • ω n
R1
(F)
Conversion gain of phase comparator
Kφ =
∴ Kφ =
VOH – VOL
1
×
2
2π
(V/rad)
VCC – GND
1
×
2
2π
(V/rad) .........*
* Approximate expression
VCO sensitivity
KV =
∆f
× 2π
∆V
(rad/V • sec)
N count (dividing ratio for VCO input signal)
N = 200
18
Application Note P14827EJ1V0AN00
C
To VCO
Loop amplifier
The following external constant values were obtained by tests using the design shown in the application circuit
example illustrated in Figure 4-1.
Loop filter circuit constants
7
C = 33 nF
To power supply
RL
R2 = 1.2 kΩ
9
To VCO
C
Cad was added for suppression of spurious
R2
signal output.
Cad = 1800 pF
10
Cad
From phase/frequency R1
comparator
1.24 kΩ
on chip
11
Internal (to IC)
External
Since the VCO oscillation frequency and the R1 and N values are all fixed in this IC, the relations between loop
filter circuit constants that optimized characteristics through experiments were obtained, and a method for easily
obtaining C and R2 from these interrelationships was evolved.
Since this IC is an active-filter type, the following circuit constant expressions for active filters are used.
Kφ • KV
R1 =
N • ω n2 • C
2•ζ
ωn =
R2 • C
From these two expressions, it follows that:
Kφ • KV • R22 • C
R1 =
N•4•ζ2
2
KV • R2 • C
R1 • 4 • ζ 2
=
N
Kφ
After testing the µPB1005K to obtain optimum characteristics, the external circuit constants for the loop filter were
found to be C = 33 nF, R2 = 1.2 kΩ (R1 is on chip). The gain of the configured VCO is:
KV = (1 725 − 1 545) MHz × 2 π / 3.0 V = 377 × 106 (rad/V • sec)
Furthermore, the following empirical value is obtained based on the values for C and R2.
KV • R22 • C
377 × 106 × 1 2002 × 33 × 10-9
=
= 89.58 × 103
N
200
Empirical value
Thus the following expression is obtained.
µPB1005K loop filter empirical expression
N
3
R2 =
× 89.58 × 10
KV • C
Where N = 200.
The KV value may vary depending on the components that are used, so the C and R2 values obtained via the
above relational expressions should be considered as a guide for obtaining optimized values via testing on your
circuit board.
Application Note P14827EJ1V0AN00
19
5.
PLL CHARACTERISTICS
5.1 Standard Spectrum Waveform and C/N Characteristics
The 1st LO monitor was used to measure the VCO’s carrier spectrum. Figure 5-1 shows the VCO carrier spectrum.
Main results
•
When VCONT voltage (1.5 V) was externally applied, the oscillation frequency became 1636.80 MHz and the VCO
sensitivity characteristics were obtained by adjusting the inductor’s mounting position. (See Figure 4-5.)
•
When the C/N value exceeds −78 dBc/Hz based on 1 kHz detuning, the characteristic of a noise level of −65
dBc/Hz generally set by GPS manufacturers is met (according to NEC’s marketing research).
Figure 5-1. VCO Carrier Spectrums (Monitored via 1st LO Monitor)
REF
−10.0 dBm ATTEN 10 dB
MKR 1.636815 GHz
−35.90 dBm
10 dB/
REF
CENTER 1.63681 GHz
RES BW 1 00 kHz
MARKER ∆
15.01 kHz
−58.80 dB
VBW 1 kHz
−10.0 dBm ATTEN 10 dB
SPAN 5.00 MHz
SWP 10.0 sec
MKR ∆ 100.0 kHz
−55.60 dB
10 dB/
CENTER 1.6368149 GHz
VBW 10 Hz
RES BW 1 kHz
REF
−20.0 dBm
VAVG 8
ATTEN 10 dB
SPAN 5.00 kHz
SWP 10.0 sec
MKR ∆ −86.67 dB/Hz
1.00 kHz
10 dB/
MARKER ∆
100.0 kHz
−55.60 dB
CENTER 1.636814 GHz
VBW 30 Hz
RES BW 3 kHz
20
MKR ∆ 15.01 kHz
−58.80 dB
10 dB/
MARKER ∆
1.636815 GHz
−35.90 dBm
REF
−10.0 dBm ATTEN 10 dB
MARKER ∆
1.00 kHz
−86.67 dB/Hz
SPAN 201 kHz
SWP 10.0 sec
CENTER 1.63660063 GHz
RES BW 100 Hz VBW 30 Hz
Application Note P14827EJ1V0AN00
SPAN 10.00 kHz
SWP 4.6 sec
5.2 Lockup Time Characteristics
The lockup time was checked using a board assembled from the application circuit example. The lockup time of
the PLL synthesizer at power-on was measured for the reference characteristics of the application circuit example.
The power supply equipment for the circuit’s power supply pin was replaced with a pulse generator and the supply
voltage (3 V) was turned ON and OFF repeatedly, after which the zero-span mode of the spectrum analyzer was
used to analyze the VCO carrier leak signal at the 1st LO monitor pin, and the length of time until the 1.6368 GHz
oscillation power comes within ±1 dB and reaches lockup was measured. Figure 5-2 shows the trace plot data for the
rising edge of the carrier in the zero-span mode. The lockup time from power-on to normal operation was
approximately 90 µs.
Figure 5-2. Measurement of Lockup Time (via Spectrum Analyzer in Zero-Span Mode)
ATTEN 10 dB
RL 0 dBm
10 dB/
90 µ s
3V
0V
CENTER 1.636801 GHz
RBW 1.0 MHz
VBW 3.0 MHz
SPAN 0 Hz
SWP 500 µ s
5.3 2nd IF Output Spectrum Characteristics
Figure 5-3 shows the 2nd IF output spectrum characteristics. This spectrum was measured using a spectrum
analyzer to monitor the 2nd IF output frequency based on a −100 dBm input level to the first RF amplifier
(µPC2749TB) in the application circuit example.
Application Note P14827EJ1V0AN00
21
Figure 5-3. 2nd IF Output Spectrum Characteristics
REF 10.0 dBm ATTEN 20 dB
Figure 5-4. Measurement Circuit
MKR 4.092 GHz
−30.00 dBm
10 dB/
2nd IF
OUT
<22>
MARKER
4.092 MHz
−30.00 dBm
1.95 kΩ
50
Ω
SA
START 100 kHz
RES BW 30 kHz
VBW 1 kHz
STOP 8.00 MHz
SWP 290 msec
Figure 5-3 shows the 2nd IF output spectrum characteristics, and Figure 5-4 shows the measurement circuit that
was used. The 2nd IF output power specification for this IC is −14.5 dBm (MIN.), but a value of −30.0 dBm was
detected in the measurement data in Figure 5-3. The specification is the value from the voltage gain, whereas the
measurement value of the spectrum analyzer in Figure 5-3 is due to the power gain.
Since this data is obtained via the measurement circuit shown in Figure 5-4, which includes a 1.95 kΩ load and an
instrument impedance of 50 Ω, the actual value must be converted as follows.
Output power
= (read value of spectrum analyzer) + 10 log (2000/50)
= (read value of spectrum analyzer) + 16 dBm.
Thus, calculation of the measurement data in Figure 5-3 yields the following:
2nd IF output power = −30 dBm + 16 dBm = −14 dBm
Figure 5-5 shows the 2nd IF output amplitude measured with an oscilloscope. An output amplitude value
exceeding 600 mVP-P was detected for a −100 dBm input level to the application circuit’s first RF amplifier
(µPC2749TB). This data indicates a square wave of approximately 800 mVP-P.
22
Application Note P14827EJ1V0AN00
Figure 5-5. 2nd IF Output Amplitude
200 mV
0.00s
Freq (1) = 4.092 MHz
6.
50 ns /
VP-P (1) = 862.5 mV
CONCLUSION
The above has described the usage and applications of the µPB1005K RF/IF down-converter + PLL frequency
synthesizer ICs for GPS receivers. Refer to the appendix for characteristics concerning examples of commercially
available components used as external components for this IC.
Application Note P14827EJ1V0AN00
23
APPENDIX
(1)
Smith charts for input/output ports (VCC = 3.0 V)
S11
1: 19.184 Ω
−52.871 Ω
2.0068 pF
1 575.420 000 MHz
RF-MIXin
MARKER1...1.57542 GHz
S11
1: 271.94 Ω
−945.25 Ω
2.7431 pF
61.380000 MHz
RF-MIXin
MARKER1...61.38 MHz
1
1
START 1 000 . 000 000 MHz STOP 2 000.000 000 MHz
S22
1: 24.140 Ω
2.1191 Ω 5.4948 nH
61.380000 MHz
RF-MIXout
MARKER1...61.38 MHz
START 10 . 000 000 MHz STOP 100.000 000 MHz
S11
1: 3.9248 kΩ
−3.8625 kΩ
10.07 pF
4.092000 MHz
2nd IFin1
MARKER1...4.092 MHz
1
1
START 10.000 000 MHz STOP 100.000 000 MHz
24
START 0.500 000 MHz STOP 10.000 000 MHz
Application Note P14827EJ1V0AN00
(2)
External filter example and characteristics (For corresponding components, refer to Table 4-1 Ratings for
External Capacitors and Resistors.)
Source: Toko, Inc.
TDF3A-1575B-10
20
50
25
60
30
70
35
80
40
90
45
Span: 500 MHz
Center Frequency : 1575 MHz
50
1.97 dB max.
Passband Insertion Loss
Passband Ripple
0.08 dB
Passband V.S.W.R.
1.27 max.
36.11 dB
at 1,540.40 MHz
10.72 dB
at 1,610.40 MHz
9.00 dB
at 1,715.40 MHz
33.15 dB
OUT
T max.
5.7
Specifications
Center Frequency (Fo)
Passband Width
Input Output Impedance
Insertion Loss in Passband
Ripple in Passband
V.S.W.R. in Passband
Attenuation
GND
4.7
A = 5.6
B = 2.5
C = 3.0
Attenuation
at 1,435.40 MHz
1.0
40
Marking.
B
15
1.2
10
30
1.2
20
IN
GND
1.0
5
Return Loss (dB)
10
100
Toko No. : TDF3A-1575B-10
Dimensions
0
A ± 0.5.
Sample No. : 1
0
Attenuation (dB)
DIELECTRIC BANDPSS FILTER
TDF Series
Tolerance : ±0.3
Unit
: mm
:
:
:
:
:
:
:
:
:
1575.4 MHz
Fo ± 5.0 MHz
50 Ω
2.7 dB max.
1.0 dB max.
2.0 max.
7.0 dB min. at Fo ± 35 MHz
30 dB min. at Fo ± 140 MHz
28 dB min. at Fo ± 140 MHz
Date: 95.11.06
Instrument : WILTRON 37269A
5CCEW
<6>
662BBX-037
:3.04.23 12:16
MO
10 dB
−53.15 dB
1 dB/
−4.65 dB
MKR[ 250]:61.38 MHz
−3.45 dB
A[*]:MAGTD
−3.32 dB
B[*]:B
<4>
INSTRUMENTS
3577A (hp)
1 kΩ
<1><2><3>
1 kΩ
Use pins 4 and 6
in a floating state.
CF:61.38 MHz
OUT[B]:0.00 dBm ST:4.20 sec
IRG[R]:0 dBm IRG[T]:0 dBm
MAGTD
SPAN :100 MHz
EL:0.00 cm
RBM:10 kHz VBW:10 kHz 50 Ω
OFFSET CTR
Measurement circuit (Bottom view)
Rin
Key
Rin
Rout
= 50 Ω
Rout = 50 Ω
ATTENUAION [dB]
1 dB /div.
5 MHz /div.
0
1.4
10
1.2
20
1
30
0.8
40
0.6
50
0.4
60
0.2
70
0.1
<1><2><3> <4><5><6>
GROUP DELAY [ µ sec]
10 dB /div.
10 MHz /div.
0
0.2
0.5
1
2
FREQUENCY [MHz]
5
10
<12><11><10> <9><8><7>
Caution
For details concerning the characteristics of external components, contact the respective manufacturers.
Application Note P14827EJ1V0AN00
25
Reference oscillator (TCXO)
Source: Kinseki
(VC-) TCXO-201C1
Temperature compensation crystal oscillator/TCXO, VC-TCXO
• Features
•
For cellular phone (VC-) TCXO
•
Surface-mounting (ceramic base) type enabling automatic mounting
•
Low profile, 2.4 mm high
•
Reflow soldering can be used.
• Package Dimensions
0.72
0.8
2.54
9.6 ± 0.3
2.4 ± 0.1
11.4 ± 0.3
(VC-) TCXO-201C1
4
5
6
7
1
8−R0.25
1.0 ± 0.1
8
1.0 ± 0.1
CONNECTION
1 : NC
4 : GND
5 : OUTPUT
6 : GND
7 : VC VC-TCXO
NC TCXO
8 : +DC
Dimensions (mm)
• Specifications
Parameter
TCXO-201C1
Note 1
VC-TCXO-201C1
Part No.
Reference frequency
12.8, 13.0, 14.4, 14.85, 15.36, 19.2, 19.68 MHz
±2.5 × 10−6/−30 to +75 °CNote 2
Frequency stability
±1 × 10−6MAX./year
Secular change
Supply voltage
+5 V ± 5%
Consumption current
2.0 mA MAX.
Output
Note 3
Output load
10 kΩ /10 pF
Output level
1VP-P MIN. (DC cut)
±3 × 10−6MIN.
Frequency variable range
Control voltage frequency characteristic
±4 × 10−6MIN./+2.5 ± 2V (normal direction)
Volume
0.27 cc
Notes 1. For the reflow conditions, contact an NEC sales representative.
6
2. Product with frequency stability of ±1.5 × 10− /−20 to +75 °C can also be manufactured.
3. Products with as supply voltage of 3.0 V can also be manufactured.
Caution
26
For the detailed characteristics of the external component examples, contact an NEC sales representative.
Application Note P14827EJ1V0AN00
(3)
Related documents
Application Note
Fundamentals of Frequency Synthesizer Circuits Employing Phase-Locked Loop
Document No.: P12196E
(Old Document No.: IEB-1003)
Data Sheet
µPB1005K
Document No.: P14016E
Data Sheet
µPC2749TB
Document No.: P13489E
Application Note
Use and Application of Silicon High-Frequency Wideband Amplifier MMIC (µPC2749TB, etc.)
Document No.: P11976E
Application Note P14827EJ1V0AN00
27
[MEMO]
28
Application Note P14827EJ1V0AN00
[MEMO]
Application Note P14827EJ1V0AN00
29
[MEMO]
30
Application Note P14827EJ1V0AN00
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