P14827EJ1V0AN00 [ETC]
uPB1005K RF/IF Down-Converter+PLL Frequency Synthesizer ICs for GPS Receivers ; 用于GPS接收机uPB1005K RF / IF下变频器+ PLL频率合成器IC\n
| 型号： | P14827EJ1V0AN00 |
| 厂家： | 
ETC |
| 描述： | uPB1005K RF/IF Down-Converter+PLL Frequency Synthesizer ICs for GPS Receivers
|
| 文件： | 总31页 (文件大小：167K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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]
Application Note P14827EJ1V0AN00
2
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.
•
•
No part of this document may be copied or reproduced in any form or by any means without prior
written consent of NEC. NEC assumes no responsibility for any errors that may appear in this document.
NEC does not assume any liability for infringement of patents, copyrights or other intellectual property rights of
third parties by or arising from the use of NEC semiconductor products listed in this document or any other
liability arising from the use of such products. No license, express, implied or otherwise, is granted under any
patents, copyrights or other intellectual property rights of NEC or others.
•
•
•
Descriptions of circuits, software and other related information in this document are provided for illustrative
purposes in semiconductor product operation and application examples. The incorporation of these
circuits, software and information in the design of customer's equipment shall be done under the full
responsibility of customer. NEC assumes no responsibility for any losses incurred by customers or third
parties arising from the use of these circuits, software and information.
While NEC endeavours to enhance the quality, reliability and safety of NEC semiconductor products, customers
agree and acknowledge that the possibility of defects thereof cannot be eliminated entirely. To minimize
risks of damage to property or injury (including death) to persons arising from defects in NEC
semiconductor products, customers must incorporate sufficient safety measures in their design, such as
redundancy, fire-containment, and anti-failure features.
NEC semiconductor products are classified into the following three quality grades:
"Standard", "Special" and "Specific". The "Specific" quality grade applies only to semiconductor products
developed based on a customer-designated "quality assurance program" for a specific application. The
recommended applications of a semiconductor product depend on its quality grade, as indicated below.
Customers must check the quality grade of each semiconductor product before using it in a particular
application.
"Standard": Computers, office equipment, communications equipment, test and measurement equipment, audio
and visual equipment, home electronic appliances, machine tools, personal electronic equipment
and industrial robots
"Special": Transportation equipment (automobiles, trains, ships, etc.), traffic control systems, anti-disaster
systems, anti-crime systems, safety equipment and medical equipment (not specifically designed
for life support)
"Specific": Aircraft, aerospace equipment, submersible repeaters, nuclear reactor control systems, life
support systems and medical equipment for life support, etc.
The quality grade of NEC semiconductor products is "Standard" unless otherwise expressly specified in NEC's
data sheets or data books, etc. If customers wish to use NEC semiconductor products in applications not
intended by NEC, they must contact an NEC sales representative in advance to determine NEC's willingness
to support a given application.
(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
3
[MEMO]
Application Note P14827EJ1V0AN00
4
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 ultra-
fine 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.
Application Note P14827EJ1V0AN00
6
3. PRODUCT FEATURES
3.1 Main Features
The main features of this new product are summarized below.
(1) Double conversion method:
(2) High integration of RF block:
Enables use of dielectric RF filter.
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
vicinity of the VCO carrier, which facilitates loop filter design.
Accepts a higher frequency for 1st IF, which makes it easier to
reduce spurious emissions due to insertion of LC filters for the 1st
and 2nd IF.
(6) Enables effective use of external filter:
(7) 2nd IF output by clipped wave:
An on-chip differential 2nd IF amplifier provides a limiter effect.
When necessary, an external control circuit can be connected to
enable auto gain control.
(8) Gain adjustment enabled in IF mixer:
(9) Reference frequency:
16.368 MHz
(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
Reference frequency
2nd IF frequency
Receiving frequency
Power supply voltage
Power consumption
Package
µPB1005K
16.368 MHz
4.092 MHz
1 575.42 MHz
2.7 to 3.3 V
45.0 mA
36-pin plastic QFN
Application Note P14827EJ1V0AN00
7
Figure 3-1. µPB1005K Pin Configuration and Internal Block Diagram
27
26
25
24
23
22
21
20
19
IF-MIXout
28
29
30
31
18
17
16
15
14
13
12
11
10
N.C.
N.C.
REFin
V
GC
N.C.
(IF-MIX)
2
GND
(Divider block)
V
CC
(IF-MIX)
8
N.C. 32
LOout
25
VCC
33
34
IF-MIXin
(Divider block)
PD
GND
(Phase detector)
GND
(IF-MIX)
RF-MIXout 35
PD-Vout
PD-Vout
1
2
V
CC
36
(RF-MIX)
1
2
3
4
5
6
7
8
9
Application Note P14827EJ1V0AN00
8
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
4 – C0.5
6.0 ± 0.2
Pin 36
Pin 1
0.22 ± 0.05
0.6 ± 0.1
6.2 ± 0.2
6.0 ± 0.2
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)
2nd IFout
REFout
1 000
pF
µ
0.1
F
1.95 kΩ
µ
10 000 1 000
0.1
F
1 000 pF
1 000 pF
pF
pF
2nd IF filter
27 26 25 24 23 22 21 20 19
µ
0.01
F
28
29
30
31
32
33
34
35
36
18
1 000 pF
17
16
15
14
13
12
11
10
TCXO
1 000 pF
1 000 pF
V
GC
1 000 pF
2
µ
1
F
8
LOout
1 000 pF
1 000 pF
25
1 000 pF
PD
1st IF filter
1st LO
monitor
1 000 pF
1 000 pF
6.8
nH
1
2
3
4
5
6
7
8
9
RFin
RF amplifer
RF filter
1 000 pF
24
pF
1.2 kΩ
1 000 pF
1 pF
24
pF
33 nF
6.2 kΩ
1 000 pF
4.7 kΩ
4.7 kΩ
3.9 nH
1 800 pF
1 000 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:
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.
<3> 1st LO ex-in:
Application Note P14827EJ1V0AN00
10
Figure 4-2. Application Evaluation Board Implementation Example
(a) Top view
70 mm
NEC
1st LO
monitor
2nd
IF
out
C7
2nd
IF
filter
C10
C11
C9 C8
TCXO
out
µ
PB1005K
RF in
C5
R4
C4
R3
R2
C13
C2
R1
C1
L1
C3
1st LO
ex-in
LO out
PB1005K
µ
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
C24
22
C21
C
16
C
C
15
14
V-D R5
L2
RF
filter
C25
C23
TCXO
Application Note P14827EJ1V0AN00
12
Table 4-1. Ratings for External Capacitors and Resistors
Component Type
Chip capacitor
Symbol
Rating
1 pF
C1
C2, C5, C6, C10, C12, C13, C16 to C19, C21 to C25
1 000 pF
1 800 pF
33 nF
C3
C4
C7, C8
C9
0.1 µF
0.01 µF
1 µF
C11
C14, C15
C20
L1
24 pF (UJ)
10 000 pF
6.8 nH
3.9 nH
6.2 kΩ
4.7 kΩ
1.2 kΩ
0 Ω
Chip inductor
Chip resistor
L2
R1
R2, R5
R3
R4
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
RF amplifier
Type
Part number
µPC2749TB
Manufacturer
NEC
SiMMIC
RF filter
Dielectric BPF
BPF for LC
Type TDF, TDF3A-1575B-10
Type 5CCEW, 662BBX-037
Type FST, 630LKN-1006
LL1608-F3N9S (3.9 nH)
1SV285
Toko
1st IF filter
Toko
2nd IF filter
LPF for LC
Toko
Inductor for VCO
V-Di
Layer-built chip L
Varactor diode
Toko
Toshiba
Toshiba
Kinseki
Output buffer
Reference signal oscillator
TC7S04F, etc.
TCXO
TCXO-201C1 (16.368 MHz)
Caution The external components and their characteristics are presented in summary form. For details
concerning these external components, including these filters, contact the respective man-
ufacturers.
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
log MAG.
S
11
S
11
REF 0.0 dB
REF 1.0 Units
1
10.0 dB/
1
200.0 m Units/
42.783 Ω 4.3164 Ω
−20.731 dB
CENTER
1.57542 GHz
MARKER 1
1.57542 GHz
1
START 1.075420000 GHz
START 1.075420000 GHz
STOP
2.075420000 GHz
STOP
2.075420000 GHz
(b) When ZL = 100 Ω
log MAG.
S
11
S
11
REF 0.0 dB
REF 1.0 Units
1
10.0 dB/
1
200.0 m Units/
74.668 Ω −42.637 Ω
−8.5229 dB
CENTER
1.57542 GHz
MARKER 1
1.57542 GHz
1
START 1.075420000 GHz
STOP 2.075420000 GHz
START 1.075420000 GHz
STOP 2.075420000 GHz
Application Note P14827EJ1V0AN00
14
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
S
11
S
11
log MAG.
REF 0.0 dB
REF 1.0 Units
1
10.0 dB/
−25.737 dB
1
200.0 mUnits/
49.246 Ω −4.7383 Ω
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
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)
V
CC
Internal (to IC)
3
V
CC
To RF-MIX or
prescaler input
amplifier
External
DC cut
DC cut
4
5
6
L
Control voltage
(from PLL loop filter)
Application Note P14827EJ1V0AN00
16
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
Using CH Standard for DC Cut Capacitor
Figure 4-7. VCO Sensitivity Characteristics when
Using UJ Standard for DC Cut Capacitor
3.5
3.0
2.5
3.5
3.0
2.5
TA = +85 ˚C
T
A
= +85 ˚C
2.0
1.5
1.0
0.5
0
2.0
1.5
1.0
0.5
0
T = +25 ˚C
A
T = +25 ˚C
A
T = −40 ˚C
A
T
A
= −40 ˚C
0
1.50
1.55
1.60
1.65
1.70
1.75
0
1.50
1.55
1.60
1.65
1.70
1.75
VCO oscillation frequency for 1st LO fVCO (GHz)
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
•
2
ω n
Kφ KV
R1 =
R2 =
CC =
(Ω)
(Ω)
C
R2
•
•
N
C
•
2
ζ
C
Phase/frequency
comparator output
To VCO
Loop amplifier
R1
•
ω n
1
(F)
•
•
R2 (5 to 10) ω n
Conversion gain of phase comparator
VOH – VOL
2
1
2π
Kφ =
Kφ =
×
(V/rad)
VCC – GND
2
1
2π
×
(V/rad) .........*
* Approximate expression
VCO sensitivity
∆f
∆V
•
KV =
× 2π
(rad/V sec)
N count (dividing ratio for VCO input signal)
N = 200
Application Note P14827EJ1V0AN00
18
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
9
To power supply
C = 33 nF
RL
R2 = 1.2 kΩ
To VCO
C
Cad was added for suppression of spurious
signal output.
R2
Cad = 1800 pF
10
C
ad
R
1
From phase/frequency
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
ζ
C
•
2
ωn =
•
R2
C
From these two expressions, it follows that:
2
•
•
• C
Kφ KV R2
R1 =
2
•
•
N
4 ζ
2
KV R22
R1
4 ζ
Kφ
•
• C
•
•
=
N
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:
6
•
KV = (1 725 − 1 545) MHz × 2 π / 3.0 V = 377 × 10 (rad/V sec)
Furthermore, the following empirical value is obtained based on the values for C and R2.
KV R22
377 × 106 × 1 2002 × 33 × 10-9
•
• C
=
= 89.58 × 103
N
200
Empirical value
Thus the following expression is obtained.
µPB1005K loop filter empirical expression
N
R2 =
× 89.58 × 103
• C
KV
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)
MKR 1.636815 GHz
MKR ∆ 15.01 kHz
−58.80 dB
−35.90 dBm
REF −10.0 dBm ATTEN 10 dB
10 dB/
REF −10.0 dBm ATTEN 10 dB
10 dB/
MARKER ∆
1.636815 GHz
−35.90 dBm
MARKER ∆
15.01 kHz
−58.80 dB
CENTER 1.63681 GHz
RES BW 1 00 kHz
CENTER 1.6368149 GHz
RES BW 1 kHz
SPAN 5.00 MHz
SWP 10.0 sec
SPAN 5.00 kHz
SWP 10.0 sec
VBW 1 kHz
VBW 10 Hz
MKR ∆ 100.0 kHz
−55.60 dB
VAVG 8
MKR ∆ −86.67 dB/Hz
REF −10.0 dBm ATTEN 10 dB
10 dB/
REF −20.0 dBm ATTEN 10 dB 1.00 kHz
10 dB/
MARKER ∆
100.0 kHz
−55.60 dB
MARKER ∆
1.00 kHz
−86.67 dB/Hz
CENTER 1.636814 GHz
RES BW 3 kHz
SPAN 201 kHz
SWP 10.0 sec
CENTER 1.63660063 GHz
SPAN 10.00 kHz
SWP 4.6 sec
VBW 30 Hz
VBW 30 Hz
RES BW 100 Hz
Application Note P14827EJ1V0AN00
20
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 µs
3 V
0 V
CENTER 1.636801 GHz
RBW 1.0 MHz
SPAN 0 Hz
SWP 500 µs
VBW 3.0 MHz
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
Figure 5-4. Measurement Circuit
MKR 4.092 GHz
−30.00 dBm
REF 10.0 dBm ATTEN 20 dB
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
STOP 8.00 MHz
SWP 290 msec
VBW 1 kHz
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.
Application Note P14827EJ1V0AN00
22
Figure 5-5. 2nd IF Output Amplitude
200 mV
0.00s
50ns /
Freq (1) = 4.092 MHz
VP-P (1) = 862.5 mV
6. 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)
S
11 1: 19.184 Ω −52.871 Ω 2.0068 pF
1 575.420 000 MHz
RF-MIXin
S11 1: 271.94 Ω −945.25 Ω 2.7431 pF
61.380000 MHz
RF-MIXin
...
...
MARKER1 61.38 MHz
MARKER1 1.57542 GHz
1
1
START 1 000 . 000 000 MHz STOP 2 000.000 000 MHz
START 10 . 000 000 MHz STOP 100.000 000 MHz
S
22 1: 24.140 Ω 2.1191 Ω 5.4948 nH
61.380000 MHz
RF-MIXout
S11 1: 3.9248 kΩ −3.8625 kΩ 10.07 pF
4.092000 MHz
2nd IFin1
...
...
MARKER1 4.092 MHz
MARKER1 61.38 MHz
1
1
START 10.000 000 MHz STOP 100.000 000 MHz
START 0.500 000 MHz STOP 10.000 000 MHz
Application Note P14827EJ1V0AN00
24
(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
DIELECTRIC BANDPSS FILTER
TDF Series
Toko No.
: TDF3A-1575B-10
Sample No. : 1
Dimensions
0
10
20
30
40
50
60
70
80
90
100
0
IN
GND
OUT
5
Marking.
10
15
20
25
30
35
40
45
50
GND
max.
T
4.7
5.7
A = 5.6
B = 2.5
C = 3.0
Tolerance : ±0.3
Unit : mm
Specifications
Center Frequency (Fo)
Passband Width
Input Output Impedance
: 1575.4 MHz
: Fo ± 5.0 MHz
: 50 Ω
Span: 500 MHz
Center Frequency : 1575 MHz
Insertion Loss in Passband : 2.7 dB max.
1.97 dB max.
0.08 dB
Passband Insertion Loss
Passband Ripple
Passband V.S.W.R.
Attenuation
Ripple in Passband
V.S.W.R. in Passband
Attenuation
: 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
1.27 max.
at 1,435.40 MHz
at 1,540.40 MHz
at 1,610.40 MHz
at 1,715.40 MHz
36.11 dB
10.72 dB
9.00 dB
33.15 dB
Date: 95.11.06
Instrument : WILTRON 37269A
<6>
<4>
INSTRUMENTS
3577A (hp)
5CCEW
662BBX-037
:3.04.23 12:16
MO
MKR[ 250]:61.38 MHz
A[*]:MAGTD
B[*]:B
1 kΩ
1 kΩ
10 dB
−53.15 dB
−4.65 dB
−3.45 dB
−3.32 dB
Use pins 4 and 6
in a floating state.
<1><2><3>
1 dB/
10 dB /div.
10 MHz /div.
0
10
20
30
40
50
60
70
1.4
1.2
1
1 dB /div.
5 MHz /div.
µ
0.8
0.6
0.4
0.2
0
CF:61.38 MHz
SPAN :100 MHz
OUT[B]:0.00 dBm ST:4.20 sec
IRG[R]:0 dBm IRG[T]:0 dBm
MAGTD
EL:0.00 cm
RBM:10 kHz VBW:10 kHz 50 Ω
OFFSET CTR
Measurement circuit (Bottom view)
Rin
Rin = 50 Ω
Key
Rout = 50 Ω
0.1
0.2
0.5
1
2
5
10
Rout
FREQUENCY [MHz]
<1><2><3> <4><5><6>
<12><11><10> <9><8><7>
Caution For details concerning the characteristics of external components, contact the respective man-
ufacturers.
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
(VC-) TCXO-201C1
9.6 ± 0.3
4
1
5
6
7
8
CONNECTION
1 : NC
4 : GND
5 : OUTPUT
6 : GND
8−R0.25
7 : VC VC-TCXO
NC TCXO
8 : +DC
1.0 ± 0.1
1.0 ± 0.1
Dimensions (mm)
• Specifications
Parameter
TCXO-201C1
VC-TCXO-201C1Note 1
Part No.
Reference frequency
Frequency stability
Secular change
Supply voltage
Consumption current
Output
12.8, 13.0, 14.4, 14.85, 15.36, 19.2, 19.68 MHz
6
±2.5 × 10− /−30 to +75 °CNote 2
6
±1 × 10− MAX./year
+5 V
± 5%Note 3
2.0 mA MAX.
10 kΩ /10 pF
1VP-P MIN. (DC cut)
Output load
Output level
6
Frequency variable range
±3 × 10− MIN.
6
Control voltage frequency characteristic
Volume
±4 × 10− MIN./+2.5 ± 2V (normal direction)
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 For the detailed characteristics of the external component examples, contact an NEC sales representative.
Application Note P14827EJ1V0AN00
26
(3) Related documents
Application Note
Fundamentals of Frequency Synthesizer Circuits Employing Phase-Locked Loop
Document No.: P12196E
(Old Document No.: IEB-1003)
Document No.: P14016E
Document No.: P13489E
Data Sheet
µPB1005K
Data Sheet
µPC2749TB
Application Note
Use and Application of Silicon High-Frequency Wideband Amplifier MMIC (µPC2749TB, etc.)
Document No.: P11976E
Application Note P14827EJ1V0AN00
27
[MEMO]
Application Note P14827EJ1V0AN00
28
[MEMO]
Application Note P14827EJ1V0AN00
29
[MEMO]
Application Note P14827EJ1V0AN00
30
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