A Receiver Using Romeo2 (Step-by-step Design for ISM Bands)

Freescale Semiconductor
Application Note
A Receiver Using Romeo2
Step-by-step Design for ISM Bands
by: Laurent Gauthier
Access and Remote Control
Toulouse, France
© Freescale Semiconductor, Inc., 2004. All rights reserved.
AN2830
Rev. 0, 9/2004
Introduction
Introduction
This document provides a step-by-step approach to designing an optimized receiver using Romeo21.
Even though the description is based on a 433.92 MHz design, bills of material are provided for almost
any ISM band: 315 MHz, 433.92 MHz, 868.3 MHz, and 916.5 MHz.
Romeo2 Presentation
Main Features
Romeo2 is a highly integrated UHF super heterodyne2 receiver designed for data transfer application. Its
local oscillator is a PLL clocked by a crystal oscillator.
Some specific features are:
•
A data manager, able to detect a programmable word in a Manchester coded RF frame and to
transmit the demodulated signal on the SPI port
•
A strobe oscillator, to do a RUN/SLEEP cycle without the help of the MCU, for lower system power
consumption
•
Dual modulation type capability; Romeo2 can switch from ASK to FSK in software.
•
LQFP24 package
Romeo2 is controlled through several pins:
•
SCLK, MOSI, MISO, RESETB: signal for the SPI port
•
STROBE: connection to the external R and C that define the oscillation frequency. Also allows
Romeo2 to be driven by the MCU
•
RFIN: RF signal input
Figure 1. Romeo2
1. Romeo2 is the codename for MC33591FTA. For more technical data, refer to the MC33591FTA specification available on the
Freescale Semiconductor web site at http://www.freescale.com.
2. A super heterodyne receiver converts the RF signal to an IF signal by mixing it with a local signal produced by an oscillator.
The IF signal is usually at a low frequency, which simplifies filtering and amplification.
A Receiver Using Romeo2, Rev. 0
2
Freescale Semiconductor
Romeo2 Presentation
Typical Application
A simple RF receiver can be realized with few external components.
C1
C3
R1
20
21
22
19
GNDDIG
RCBGAP
STROBE
CAFC
MIXOUT
GNDLNA
17
16
15
14
13
CAGC
DMDAT
18
12
7
RESETB
XTAL2
GNDSUB
PFD
6
MISO
11
C17
MC33591
RFIN
XTAL1
5
MOSI
10
C11
SCLK
GND
4
VCC
VCCDIG
U1
VCCLNA
R3
C6
VCC
9
3
GNDVCO
2
C9
L4
VCC
8
1
CMIXAGC
VCC
C7
23
R2
24
C2
C20
C19
R10
C21
C23
J8
J7
J6
J5
J4
J3
J2
RESETB
MISO
MOSI
SCLK
STROBE
VCC
GND
RFIN
C24
GNDDIG
X1
J13 J12
Figure 2. A Typical Application
U1 is Romeo2. The external crystal X1 defines the operating frequency of the internal PLL. The loop filter
of the PLL is comprised of C20, C23, and R10.
The internal AGC1 requires an external capacitor C2 to set its time constant.
C3 is required for AFC2, to adjust the center frequency of the internal IF3 amplifier.
C1 and R2 define the frequency of the strobe oscillator that sets the ON-OFF cycling of the receiver.
R3 allows the MCU to drive the state of the receiver directly.
C21 is used in OOK for the IF amplifier AGC. In the case of FSK, this capacitor is used as an internal low
pass filter.
C17, L4 and C11 form a matching network to match the RFIN impedance of Romeo2 to the impedance
of the antenna connected to J13.
R1 is used to set internal biasing.
1. Automatic Gain Control. This increases the dynamic range of the receiver (the difference between the smallest and the largest
signal the receiver can process).
2. Automatic Frequency Control. A system that uses a reference signal to adjust the frequency of a filter or receiver.
3. Intermediate Frequency amplifier in a super heterodyne receiver.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
3
RF Module Specifications
A microcontroller is used to control RESETB, MISO, MOSI, and SCLK (and STROBE if necessary).
Romeo2 internal registers can then be programmed to adjust various parameters:
•
Frequency of operation
•
Strobe oscillator operation
•
Data Manager operation (data rate and frame content, for example)
•
Mixer Gain
This simple design has the following advantages.
•
Cost effective
•
Compact
•
High sensitivity
•
Low consumption, due to the strobe oscillator
•
Low MCU overhead, due to Data Manager
However, it does have the following drawbacks.
•
Poor EMC performance in noisy environments with high level RF interference due to low filtering
effect between antenna and RFIN
•
C21 is shared in OOK and FSK; for dual operation mode and various data rates, the value of C21
is a compromise
The proposed design should not suffer these drawbacks and should maintain a high sensitivity.
RF Module Specifications
Overview
The Romeo2 RF Module is a part of a project to make a receiver for long-range remote control1.
Figure 3. Receiver Using the Romeo2 RF Module
1. The range is more than one mile outdoors. Specifications are compatible with ETSI regulations.
A Receiver Using Romeo2, Rev. 0
4
Freescale Semiconductor
Romeo2 RF Module
The receiver is composed of three parts:
•
An MCU board
•
A Romeo2 RF Module with all RF components, reusable for other design
•
An antenna
Specifications
•
Sensitivity higher than -108dBm at 1200bps (Manchester coding)
•
High out of band rejection, higher than 60dB at 1 MHz
•
Narrow baseband bandwidth to improve Signal/Noise ratio
•
Input matched to 50 Ω
•
100% ASK demodulation (OOK)
•
100kHz deviation FSK demodulation
•
5V power supply
•
Low current
This lead to the following definition of Romeo2 RF Module 433 MHz:
•
Romeo2 circuit with dedicated crystal
•
Surface Acoustic Wave Filter (SAW filter)
•
Low noise amplifier (LNA) using an external transistor
Romeo2 RF Module
Schematic
The Romeo2 RF Module is composed of three blocks.
From the antenna to the MCU, we can find:
•
An LNA with Q1 and surrounding components
•
A SAW filter F1
•
Romeo2
Some options on the board allow various configurations to be tested:
•
Romeo2 alone
•
Romeo2 and SAW filter
•
Romeo2, SAW filter and LNA
The LNA could be placed between Romeo2 and the SAW filter. This would offer lower sensitivity but but
higher resistance to interference. Because the goal of the project is to increase the range of the system
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
5
Romeo2 RF Module
with a reasonable resistance to interference, the LNA is placed at the input of the receiver, to minimize
the overall noise and maximize the sensitivity.
C1
11
J2-11 STROBE
R3
C3
R1
R2
VCC
3
4
C11
5
C27
6
C17
20
21
22
19
GNDDIG
RCBGAP
STROBE
23
MC33591
MISO
RESETB
GNDLNA
GNDSUB
PFD
C18
7
R6
MOSI
VCCLNA
RFIN
DMDAT
1
17
21
J2-21 SCLK
16
17
J2-17 MOSI
15
19
J2-19 MISO
14
27
J2-27 RESETB
23
J2-23 /SS
13
C26
R14
C20
C19
VCC
18
CAGC
3
L4
J2-1
VCC
VCCDIG
SCLK
XTAL2
5
C13
GND
12
Q1
BFR92
J2-3
C6
VCC
11
R5
4
C15
VCC
XTAL1
6
3
2
10
2
1
C9
C10
C12
C14
7
GND
L3
SMA v ert
F1
1
9
L2
8
C8
R4
J1
VCC
GNDVCO
C7
CAFC
U1
R9
8
C5
24
ENABLELNA
TP1
TEST1
MIXOUT
C2
CMIXAGC
C4
C21
ENABLELNA
25
C22
J2-25 ENABLELNA
C25
R10
C23
X1
C24
Q2
BC847
R11
R12
R13
13
J2-13 AGC
Figure 4. Initial Schematic Diagram
Around Romeo2, the typical application undergoes some minor changes.
The C21 capacitor can be paralleled with C22 switched by Q2 to adapt for different data rates or
demodulation modes. R11 pre-charges C22 to avoid current spikes, which would increase the settling
time.
C26 adds some low-pass filtering to reduce the bandwidth of the demodulated signal. C26 is removed for
high data rate operation.
Some precautions are taken with the ground connections, to ensure that digital noise does not reduce the
sensitivity. There are different grounds for the digital and analog parts of Romeo2. Both are connected to
the ground of the motherboard via two different pins GNDANA and GNDDIG.
The LNA uses a BFR92. R4 and R5 set the base voltage and R6 fixes the current. L1 allows the RF signal
to be present on the collector, while maximizing the collector DC voltage to increase linearity.
The LNA can be powered down by the MCU with the ENABLELNA pin, when Romeo2 is in sleep mode.
C14, L3, C10 and C15 provide a matching network between the antenna and the LNA.
Similarly, C12, C8, L2 and C13 match the LNA with the SAW F1 while C27, L4, C11 and C17 match the
SAW filter to Romeo2.
A Receiver Using Romeo2, Rev. 0
6
Freescale Semiconductor
Romeo2 RF Module
The SAW filter is an RF1172B from RFM1. This device is available for different frequencies2 in the same
package and are pin-to-pin compatible.
Computation of Values and Optimization
Strobe Oscillator
C1 and R2 fix the period of the strobe oscillator, Tstrobe.
This time should be long enough for Romeo2 to receive an ID3 during its wake up time. At a bit rate of
1200 bits per second, it takes 6.6 ms to receive the ID.
With C1 = 100n and R2 = 1M, Tstrobe = 12ms. This is large enough to allow Romeo2 to receive the ID
and wake up.
Crystal
To compute the frequency of X1, first select a valid divide ratio (n) for the internal clock, and the value of
the bit CF4:
•
Frf around 315 MHz: n = 8 and CF = 0
•
Frf around 433.92 MHz: n = 11 and CF = 1
Then, compute the frequency of the crystal like this: Fref = Frf/(32-0.66/(1.23*n))
This gives X1 = 13.58 MHz for Frf = 433.92 MHz
C24 = 10p and C19 = 10n, as specified in the data sheet.
Around Romeo2
Most values are taken from the data sheet.
The values of C6, C3, C7, and C9 are not critical, but these decoupling capacitors should be sited close
to U1.
R1 = 180 kΩ, 1%
C2 = 10 nF and C3 = 100 pF, as in the data sheet.
The loop filter is also the same as the data sheet: C20 = 4.7 nF, C23 = 390 pF, R10 = 1 kΩ.
To drive Q2, R12 = 47 kΩ and R13 = 10 kΩ are suitable. The current in R12 is less than
IR12 = (5-0.6)/47000 < 100 µA. It should be possible to reduce this current.
Initially, R11 is omitted.
1. RFM is a registered trademark of RF Monolithics, Inc. (www.RFM.com)
2. Available frequencies are 315 MHz, 418 MHz, 433.92 MHz, 868.35 MHz, and 916.5 MHz.
3. An ID is a 8 bit word, transmitted in the frame, that Romeo2 should detect before processing data. (See data sheet.)
4. Refer to the data sheet for information on the Romeo2 internal registers.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
7
Romeo2 RF Module
Optimum low-pass filtering is achieved with C26 = 4.7 nF; this increases the sensitivity to about 1 dB for
a 1.2 kbd data rate.
Matching Romeo2 to the SAW Filter
A network analyzer was used to measure the parameters of the SAW filter on the final board (which is
different from the one used by RFM).
At 433.92 MHz, this gives:
–
–
–
–
S11saw = 0.933 [-43.5°]
S21saw = 0.0410 [43°]
S12saw = 0.0356 [41.5°]
S22saw = 0.964 [-50°]
Note that, because S12 and S21 are low, matching to S22 is a good approximation, which will simplify the
design of the matching network.
For Romeo2, the input impedance is given in the data sheet: Zromeo = 1.4pF || 1100 Ω
A possible matching network is shown in Figure 5 and described below. One coil and one capacitor are
reversed, but the shapes of these two components are the same (0603), so this can be done.
Figure 5. Matching Network and Simple Smith Chart
This gives:
–
C17 = 3.3 pF
A Receiver Using Romeo2, Rev. 0
8
Freescale Semiconductor
Romeo2 RF Module
–
–
–
C11 = 100 pF
L4 = C16 = 6.8 pF
C27 = L6 = 22 nH
With these values, the impedance reflected to the output of the SAW filter is Z*saw = 3.63 + j113.7. This
is equivalent to a reflection coefficient of Γ =0.977 [47.4°], which is close to the conjugate of S22saw.
To optimize this matching network, the HF generator is connected to the input of the SAW, and the various
elements are adjusted to maximize the sensitivity.
This gives:
–
–
–
–
C17 = 3.9 pF
C11 = 100 pF
L4 = C16 = 8.2 pF
C27 = L6 = 15 nH
LNA polarization
To reduce the current consumption, 1 mA is a maximum limit for the collector current of Q1. To reduce
the variation of this current with temperature, it is recommended to use an emitter feedback bias network1.
Let us make the following assumptions:
–
–
–
–
–
–
Vcc = 5V
Ic = 1mA
Vbe = 0.7V
VR6 = 1V
Q1 = 100
IR5 = 100µA
We then find:
–
–
–
–
R6 = VR6/Ic = 1k
VR5 = VR6+Vbe
R5 = VR5/IR5 = 17000 Ωs
R4 = (Vcc-VR5)/(IR5+Ic/β) = 16500 Ωs
So R5 = 18k and R4 = 15k.
Some adjustments were made on the final design to have precisely 1 mA at 25°C. Those changes are:
–
–
–
R6 = 1k
R5 = 10k
R4 = 15k
1. A very useful (and free) tool to compute current variations with temperature and transistor parameters is AppCad from Agilent
Technologies. www.agilent.com
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
9
Romeo2 RF Module
LNA S-parameters
The data sheet of the BFR92 gives no S-parameter for the chosen polarization. We then need to make
some measurements on the LNA to match it.
With the network analyzer, we found, at 433.92 MHz:
–
–
–
–
S11lna = 0.845 [-70°]
S21lna = 3.49 [131°]
S12lna = 0.154 [66°]
S22lna = 0.871 [-21.2°]
It seems easy now to make a matching network; however, the analysis of S11lna was done with a large
span, and it has been discovered that S11lna was greater than unity for frequencies above 200 MHz,
which means a negative resistance or a potential instability1.
Some changes have been done on the LNA to make it unconditionally stable. L1 was replaced by a
resistor R9, and C18 was increased to 10 nF. With R9 = 1 kΩ, VCE is reduced to 3V but this does not
lead to a change in current, and R4, R5 and R6 do not require to be modified.
The measured LNA parameters are shown in Table 1.
Table 1. Measured LNA Parameters
F (MHz)
S11
mod
arg
S21
mod
arg
S12
mod
arg
S22
mod
arg
0.3
0.979
-10.4
0.761
-54.8
0.015
-82
0.960
-2.72
1
0.979
-1.1
0.739
-113
0.011
-74
0.958
-2.66
10
0.950
-2.33
3.53
-173
0.0026
72
0.920
-2.04
100
0.907
-18.3
3.50
157.3
0.026
76
0.890
-9.44
200
0.829
-35
3.457
133.5
0.05
62
0.850
-18.5
315
0.710
-51.9
3.19
103.8
0.074
43.5
0.789
-26.9
418
0.605
-63.5
2.79
82.9
0.077
33.3
0.746
-32.68
434
0.600
-65.52
2.681
81.14
0.087
32.2
0.748
-33.9
600
0.458
-80.8
2.288
50.58
0.107
16.2
0.686
-42.55
700
0.395
-88.6
2.121
35.27
0.123
9.22
0.658
-48.03
868
0.293
-100.9
1.911
7.58
0.150
-5.2
0.607
-56.64
1000
0.248
-108.4
1.708
-8.57
0.167
-11.5
0.592
-65.43
1500
0.0548
-157.5
1.353
-77.7
0.281
-57.1
0.460
-100
2000
0.148
23.1
1.157
-143.2
0.448
-112.3
0.379
-156.8
1. For an active element, the S-parameters should always be verified in a larger frequency span than the band of interest. An
oscillation in the LNA can reduce the sensitivity or lead to bad EMC performances.
A Receiver Using Romeo2, Rev. 0
10
Freescale Semiconductor
Romeo2 RF Module
Table 1. Measured LNA Parameters (Continued)
F (MHz)
S11
mod
arg
S21
mod
arg
S12
mod
arg
S22
mod
arg
2500
0.323
-24.2
0.887
156.2
0.541
-175
0.330
124.7
3000
0.452
-64.2
0.780
104.6
0.615
123.6
0.320
54
So, at 433.92 MHz:
–
–
–
–
S11lna = 0.6 [-65.52°]
S21lna = 2.681 [81.14°]
S12lna = 0.087 [32.2°]
S22lna = 0.748 [-33.9°]
The gain of the LNA is slightly reduced (S21lna is lower), but the isolation is increased (S12lna is lower
too), thus increasing the stability.
Matching the SAW to the LNA
A Touchstone file has been made with the S-parameters of the LNA. This allows the impedance and gain
of the system to be computed.
The load is the SAW with saw = 0.933 [-43.5°].
The matching network is adjusted in the software to provide maximum gain of the system. In this
configuration, the computed gain is about 10 dB with the input of the LNA not yet matched.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
11
Romeo2 RF Module
Figure 6. Matching the SAW to the LNA
This gives:
–
–
–
–
C13 = 1.8 pF
L2 = 47 nH
C8 = 27 pF
C12 = 5.6 pF
To optimize this matching network, the HF generator is connected to the input of the LNA, and the various
elements are adjusted to increase the sensitivity1.
This gives:
–
–
–
–
C13 = 1.8 pF
L2 = 47 nH
C8 = 27 pF
C12 = 3.3 pF
Once matched to the SAW, the input impedance of the LNA is ZinLNA = 6.2 - j48.4
1. This approach neglects the impedance change during optimization at the input of the LNA. But some simulations showed that
this lead to a minor error.
A Receiver Using Romeo2, Rev. 0
12
Freescale Semiconductor
Romeo2 RF Module
Matching the LNA to 50
A rule of thumb to match the input of a LNA correctly, to achieve maximum sensitivity of the system, is
first to do a normal matching network and then to adjust it. The optimum is normally not the power
matching but the minimum noise matching. This matching is most often slightly different.
This network matches the LNA to 50 with a reasonable mismatch (VSWR = 1.2), which is equivalent to a
loss of 0.036 dB.
Figure 7. Matching the LNA to 50
This gives:
–
–
–
–
C15 = 1.8 pF
C10 = 47 pF
L3 = 22 nH
C14 = 22 pF
The optimization process showed that the sensitivity was not much affected by those components.
Maximum sensitivity was achieved with:
–
–
–
–
C15 = 1.8 pF
C10 = 100pF
L3 = 33 nH
C14 = nc
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
13
Romeo2 RF Module
Final Schematic
The final schematic is the result of the optimization process.
C1
100nF
11
J2-11 STROBE
R3
1k
C3
100pF
R1
180k 1%
VCC
C11
100pF
5
6
C17
8.2pF
C18
10nF
20
21
19
GNDDIG
RCBGAP
22
23
CAFC
STROBE
MISO
RESETB
GNDLNA
GNDSUB
DMDAT
C20
4.7nF
R10
1k
C19
10nF
CAGC
C16
8.2pF
MC33591
RFIN
XTAL2
L6
15nH
MOSI
VCCLNA
GND
J2-1
VCC
18
1
17
21
J2-21 SCLK
16
17
J2-17 MOSI
15
19
J2-19 MISO
14
27
J2-27 RESETB
23
J2-23 /SS
13
C26
4.7nF
R14
10k
12
4
J2-3
VCC
SCLK
7
R6
1k
3
5
3
C6
100nF
VCCDIG
VCC
11
Q1
BFR92
6
3
VCC
XTAL1
R5
10k
2
10
C15
1.8pF
2
4
C14
1pF
C13
1.5pF
C9
100pF
GND
C12
3.9pF
7
9
C10
100pF
1
PFD
L3
18nH
SMA v ert
L2
56nH
8
C8
27pF
R4
15k
J1
C7
VCC
100nF
1
F1
RF1172B
24
U1
R9
1k
GNDVCO
C5
100p
CMIXAGC
ENABLELNA
R2
1M 1%
TP1
TEST1
MIXOUT
C2
10nF
8
C4
100p
C21
100nF
C22
470nF
ENABLELNA
25
J2-25 ENABLELNA
C25
10nF
C23
390pF
X1
13.580625MHz
C24
10pF
Q2
BC847
R12
47k
R13
10k
13
J2-13 AGC
Figure 8. Final Optimized Schematic Diagram
How to use the Romeo2 RF Module
All the logic level signals available on J1 are referred to VCC and GND.
NOTE
Do not apply any signal higher than VCC or lower than GND to the module.
A Receiver Using Romeo2, Rev. 0
14
Freescale Semiconductor
Romeo2 RF Module
VCC 1
2
GND 3
4
5
6
7
8
9
10
STROBE 11
12
AGC 13
14
15
16
MOSI 17
18
MISO 19
20
SCLK 21
22
/SS 23
24
ENABLELNA 25
26
RESETB 27
28
Connector seen from
component side
Figure 9. Connector J1 Connections
Table 2. Connector J1 Pin Assignments and Functions
Number
Name
Type
Function
1
VCC
Power supply
5V for Romeo2 and LNA.
3
GND
Power supply
To be connected to a large ground plane
11
STROBE
Input
Strobe oscillator control
0 = strobe oscillator is stopped
1 = strobe oscillator is stopped and Romeo2 is wake up
highZ = strobe oscillator is running
13
AGC
Input
AGC speed control/FSK demodulator settling time
0 = FSK at 1.2kbps
1 = OOK at 1.2kbps
17
MOSI
Input/Output
Serial data for the SPI port
19
MISO
Output
Serial data for the SPI port
21
SCLK
Input/Output
Serial clock for the SPI port
25
ENABLELNA
Input
LNA bias control
0 = LNA is OFF.
1 = LNA is ON. Normal mode during reception
27
RESETB
Input
Configuration mode/Normal mode control for the SPI port
Software and MCU Board
Refer to AN2707 for more information concerning software drivers for this Romeo2 RF Module.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
15
Measurements
Measurements
Supply Current
Supply current is measured in various configurations at Vcc = 5V.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Strobe=1 ENLNA=0
Strobe=0 ENLNA=0
Strobe=1 ENLNA=1
Strobe=0 ENLNA=1
1110
yes
315MHz
MC33591
1111
no
315MHz
MC33591
5.42
0.21
6.57
1.27
xxxxx
xxxxx
5.32
0.19
1120
yes
433.92MHz
MC33591
1121
no
433.92MHz
MC33591
Supply Current (mA)
5.65
xxxxx
0.21
xxxxx
6.80
5.33
1.28
0.17
1131
no
868.3MHz
MC33593
1141
no
916.5MHz
MC33593
xxxxx
xxxxx
7.06
0.18
xxxxx
xxxxx
7.15
0.18
OOK Sensitivity (BER Method)
A data analyzer is used to measure the BER at various RF signal levels. The RF signal is OOK modulated.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
1111
no
315MHz
MC33591
1.2kbps
OOK
ON
1110
yes
315MHz
MC33591
1.2kbps
OOK
ON
1120
yes
433.92MHz
MC33591
1.2kbps
OOK
ON
1131
no
868.3MHz
MC33593
1.2kbps
OOK
ON
1141
no
916.5MHz
MC33593
1.2kbps
OOK
ON
J
-107.4
L
-108.4
Data Analyzer Setup
2400 bps NRZ or 1200 bps Manchester
0101 0101 (NRZ)
Measurements over 2500 bits
Data Rate :
Pattern :
Curve :
Sensitivity for 1e-2 BER :
1121
no
433.92MHz
MC33591
1.2kbps
OOK
ON
A
-108.6
C
-111.0
E
-107.0
H
-108.8
A Receiver Using Romeo2, Rev. 0
16
Freescale Semiconductor
Measurements
2.0E-01
1.5E-01
1.0E-01
5.0E-02
A
C
E
H
J
L
-114.0
-113.0
-112.0
-111.0
-110.0
-109.0
-108.0
-107.0
-106.0
-105.0
-104.0
0.0E+00
-103.0
-102.0
FSK Sensitivity (BER Method)
A data analyzer is used to measure the BER at various RF signal levels. The RF signal is FSK modulated.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
Cdmdat :
1111
no
315MHz
MC33591
1.2kbps
FSK 100kHz
OFF
yes
1110
yes
315MHz
MC33591
1.2kbps
FSK 100kHz
OFF
yes
1120
yes
433.92MHz
MC33591
1.2kbps
FSK 100kHz
OFF
yes
1131
no
868.3MHz
MC33593
1.2kbps
FSK 100kHz
OFF
yes
1141
no
916.5MHz
MC33593
1.2kbps
FSK 100kHz
OFF
yes
K
-111.4
M
-108.0
Data Analyzer Setup
2400 bps NRZ or 1200 bps Manchester
0101 0101 (NRZ)
Measurements over 2500 bits
Data Rate :
Pattern :
Curve :
Sensitivity for 1E-2 BER :
1121
no
433.92MHz
MC33591
1.2kbps
FSK 100kHz
OFF
yes
B
-103.6
D
-112.2
F
-108.2
I
-108.8
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
17
Measurements
2.0E-01
1.5E-01
1.0E-01
5.0E-02
B
D
F
I
K
M
-114.0
-113.0
-112.0
-111.0
-110.0
-109.0
-108.0
-107.0
-106.0
-105.0
-104.0
0.0E+00
-103.0
-102.0
OOK Sensitivity (Functional Method)
The sensitivity is measured using an RF generator modulated by a frame generator. Software decodes
the frame and lights an LED if the frame is received correctly.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
Data Manager Off
Data Manager On
1110
yes
315MHz
MC33591
1.2kbps
OOK
ON
1111
no
315MHz
MC33591
1.2kbps
OOK
ON
1120
yes
433.92MHz
MC33591
1.2kbps
OOK
ON
1121
no
433.92MHz
MC33591
1.2kbps
OOK
ON
1131
no
868.3MHz
MC33593
1.2kbps
OOK
ON
1141
no
916.5MHz
MC33593
1.2kbps
OOK
ON
-109.4
-108.6
-106
-106
-107.6
-105.8
-105.6
-102.6
-106.4
-103.6
-107.2
-105.8
FSK Sensitivity (Functional Method)
The sensitivity is measured using an RF generator modulated by a frame generator. A software decodes
the frame and lights an LED if the frame is received correctly.
A Receiver Using Romeo2, Rev. 0
18
Freescale Semiconductor
Measurements
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
Data Manager Off
Data Manager On
1110
yes
315MHz
MC33591
1.2kbps
FSK
OFF
1111
no
315MHz
MC33591
1.2kbps
FSK
OFF
1120
yes
433.92MHz
MC33591
1.2kbps
FSK
OFF
1121
no
433.92MHz
MC33591
1.2kbps
FSK
OFF
1131
no
868.3MHz
MC33593
1.2kbps
FSK
OFF
1141
no
916.5MHz
MC33593
1.2kbps
FSK
OFF
-110.4
-110
-102
-101.8
-107.6
-107.2
-107.8
-106.8
-108
-107
-108.8
-108
Maximum Demodulated Signal (BER Method)
A data analyzer is used to measure the BER for high RF signal levels.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
1110
yes
315MHz
MC33591
1.2kbps
OOK/FSK
ON/OFF
1111
no
315MHz
MC33591
1.2kbps
OOK/FSK
ON/OFF
1120
yes
433.92MHz
MC33591
1.2kbps
OOK/FSK
ON/OFF
1121
no
433.92MHz
MC33591
1.2kbps
OOK/FSK
ON/OFF
1131
no
868.3MHz
MC33593
1.2kbps
OOK/FSK
ON/OFF
1141
no
916.5MHz
MC33593
1.2kbps
OOK/FSK
ON/OFF
OOK
FSK
> 19dBm
10.6dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
0dBm
> 19dBm
> 19dBm
Maximum Demodulated Signal (Functional Method)
The maximum demodulated level is measured using an RF generator modulated by a frame generator.
Software decodes the frame and lights an LED if the frame is received correctly.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
1110
yes
315MHz
MC33591
1.2kbps
OOK
ON
1111
no
315MHz
MC33591
1.2kbps
OOK
ON
1120
yes
433.92MHz
MC33591
1.2kbps
OOK
ON
1121
no
433.92MHz
MC33591
1.2kbps
OOK
ON
1131
no
868.3MHz
MC33593
1.2kbps
OOK
ON
1141
no
916.5MHz
MC33593
1.2kbps
OOK
ON
Data Manager Off
Data Manager On
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
13dBm
12.2dBm
14dBm
11.2dBm
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
1110
yes
315MHz
MC33591
1.2kbps
FSK
OFF
1111
no
315MHz
MC33591
1.2kbps
FSK
OFF
1120
yes
433.92MHz
MC33591
1.2kbps
FSK
OFF
1121
no
433.92MHz
MC33591
1.2kbps
FSK
OFF
1131
no
868.3MHz
MC33593
1.2kbps
FSK
OFF
1141
no
916.5MHz
MC33593
1.2kbps
FSK
OFF
Data Manager Off
Data Manager On
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
> 19dBm
9.8dBm
8.4dBm
15.4dBm
14.4dBm
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
19
Measurements
Local Oscillator Leakage
A spectrum analyzer is connected to the RF connector. The level of the local oscillator is measured.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
1110
yes
315MHz
MC33591
1111
no
315MHz
MC33591
RBW (kHz) :
Span (MHz) :
Detector :
Aquisition :
Fc (MHz) :
IF (kHz) :
Fc+IF (MHz) :
1
10
Peak
Maxhold
315
660
315.66
1
10
Peak
Maxhold
315
660
315.66
<-113
-95.91
LO Level (dBm) :
1120
yes
433.92MHz
MC33591
1121
no
433.92MHz
MC33591
Spectrum Analyzer Setup
1
1
10
10
Peak
Peak
Maxhold
Maxhold
433.92
433.92
660
660
434.58
434.58
<-113
-96.37
1131
no
868.3MHz
MC33593
1141
no
916.5MHz
MC33593
1
10
Peak
Maxhold
868.3
660
868.96
1
10
Peak
Maxhold
916.5
660
917.16
-86.94
-84.99
OOK Wake Up Time
A modulated RF generator is connected to the RF input for various levels. The STROBE pin is connected
to a square wave generator. The time between the positive edge on STROBE and the first pulses on
MOSI is measured. This measurement is done for various values of Cagc.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
RFin Power Level (dBm) :
CAGC ON
CAGC OFF
1110
yes
315MHz
MC33591
1.2kbps
OOK
ON/OFF
-100
1.52
2.08
Wake up time (ms)
-90
2.02
1.76
-80
1.72
1.42
-60
1.8
1.6
A Receiver Using Romeo2, Rev. 0
20
Freescale Semiconductor
Measurements
FSK Wake Up Time
A modulated RF generator is connected to the RF input for various levels. The STROBE pin is connected
to a square wave generator. The time between the positive edge on STROBE and the first pulses on
MOSI is measured. This measurement is done for different values of Cagc.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
RFin Power Level (dBm) :
CAGC ON
CAGC OFF
1110
yes
315MHz
MC33591
1.2kbps
FSK 50kHz
ON/OFF
-100
14.6
1.82
-90
13.44
1.4
-80
14.36
2.18
-60
13.8
2.58
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
21
Measurements
Bandwidth
An RF generator is OOK modulated by a frame generator. The level of the RF generator is adjusted to
measure the sensitivity of the receiver for various frequencies. The maximum sensitivity is defined as the
0 dB reference.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data rate :
Modulation :
Cagc :
Dmdat :
1120
yes
433.92MHz
MC33591
1.2kbps
OOK
ON
ON
A Receiver Using Romeo2, Rev. 0
22
Freescale Semiconductor
Measurements
2 MHz Span
-10
-30
-50
-70
-90
-110
-130
431.92
432.42
432.92
433.42
433.92
434.42
434.92
435.42
435.92
283.92
333.92
383.92
433.92
483.92
533.92
583.92
633.92
200 MHz Span
-10
-30
-50
-70
-90
-110
-130
233.92
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
23
Measurements
IP3, Blocking and Dynamic Range
A valid signal is applied to the RF input at a level 3dB above the sensitivity level. An interference signal
2 MHz or 10 MHz away is also applied to the RF input using a combiner. The level of the interference
signal is increased as long as the demodulation of the valid signal is correct. This gives the blocking level.
For IP3 measurements, two RF generators are used with a combiner, the frequency offsets being -5 MHz
and -10 MHz. These have the same level, but one is modulated by a frame generator. The level is
increased up to the correct demodulation of the frame. The received signal (in fact, an interference
created by the non-linearity of the receiver) has then a level equal to the sensitivity level. IP3 is computed
from the sensitivity level and RF generator levels.
IP3 = (3*SL-GL)/3
Where SL = sensitivity level and GL = generator level.
The dynamic range is then defined as the difference between the sensitivity level and IP3.
Ref :
LNA+SAW :
Frequency :
Romeo2 ref :
Data Manager :
Modulation :
Cagc :
1111
no
315MHz
MC33591
on
OOK
on
1110
yes
315MHz
MC33591
on
OOK
on
1121
no
433.92MHZ
MC33591
on
OOK
on
1120
yes
433.92MHz
MC33591
on
OOK
on
1131
no
868.3MHz
MC33593
on
OOK
on
1141
no
916.5MHz
MC33593
on
OOK
on
Sensitivity :
Sensitivity+3dB :
-108.6
-105.6
-106.0
-103.0
-105.8
-102.8
-102.6
-99.6
-103.6
-100.6
-105.8
-102.8
Interference Frequency 1 :
Interference Frequency 2 :
305.00
310.00
305.00
310.00
423.92
428.92
423.92
428.92
858.30
863.30
906.50
911.50
Interference level :
-49.5
-34.9
-48.0
-34.6
-48.7
-50.3
Interference IM3 level :
OOK Blocking level (10MHz) :
FSK Blocking level (10MHz) :
OOK Blocking level (2MHz) :
FSK Blocking level (2MHz) :
-108.6
-53.2
-48.4
-63.2
-61.4
-38.3
-22.2
-18.4
-45.2
-43.4
-50.4
-49.7
-48.6
-64.7
-62.6
-34.6
-32.7
-19.6
-48.7
-33.6
-51.3
-54.6
-52.4
-76.6
-65.4
-52.6
-51.2
-51.6
-70.2
-82.6
IP3 :
Dynamic Range :
-20.0
88.6
0.7
106.7
-19.1
86.7
-0.6
102.0
-21.3
82.3
-22.6
83.2
A Receiver Using Romeo2, Rev. 0
24
Freescale Semiconductor
CAD Files
CAD Files
Generic schematics
The following schematic diagram is a generic one that can be adapted for many configurations.
•
With or without LNA
•
With or without SAW filter
•
Different frequencies
•
Different AGC and DMDAT filtering optimizations
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
25
CAD Files
11
C1
tbd
C3
tbd
R1
tbd
VCC
L5
tbd
C29
tbd
20
21
19
GNDDIG
RCBGAP
22
DMDAT
C20
tbd
R10
tbd
STROBE
23
GNDSUB
L6
tbd
MISO
RESETB
7
R7
0
6
C17
tbd
GNDLNA
C19
tbd
J2-1
VCC
1
17
21
J2-21 SCLK
16
17
J2-17 MOSI
15
19
J2-19 MISO
14
27
J2-27 RESETB
23
J2-23 /SS
13
CAGC
C18
tbd
5
MOSI
MC33591/2/3/4
RFIN
XTAL2
C11
tbd
VCCLNA
GND
18
C26
tbd
R14
tbd
12
4
C27
tbd
R6
tbd
3
J2-3
VCC
SCLK
XTAL1
L4
tbd
3
C6
tbd
VCCDIG
VCC
11
Q1
BFR92
5
VCC
10
R5
tbd
6
3
2
GND
C15
tbd
2
4
C14
tbd
C13
tbd
1
C9
tbd
9
C12
tbd
7
GNDVCO
C10
tbd
1
VCC
PFD
L3
tbd
L2
tbd
8
C8
tbd
R4
tbd
C7
tbd
F1
tbd
CAFC
U1
L1
tbd
8
C5
tbd
MIXOUT
ENABLELNA
R2
tbd
TP1
TEST1
24
C2
tbd
CMIXAGC
C4
tbd
J2-11 STROBE
R3
tbd
C21
tbd
C22
tbd
ENABLELNA
25
J2-25 ENABLELNA
C25
tbd
C23
tbd
X1
tbd
J1
SMA v ert
C24
tbd
Q2
BC847
R11
tbd
R12
tbd
R13
tbd
13
J2-13 AGC
A Receiver Using Romeo2, Rev. 0
26
Freescale Semiconductor
CAD Files
Bill of Materials
Module reference
Frequency
Equipment
Modulation
Minimum Baud Rate
Reference
R1
R2
R3
R4
R5
R6
R7
R9 (may replace L1)
R10
R11
R12
R13
R14
R20 (may replace L4)
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16 (may replace L4)
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C29
L1
L2
L3
L4
L5
L6
Q1
Q2
F1
U1
X1
J1
J2
Package
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
SOT23
SOT23
1110
315MHz
LNA+SAW
OOK/FSK
1.2kbps
180k 1%
1M 1%
1k
15k
10k
1k
not equiped
1k
1k
not equiped
47k
10k
10k
not equiped
100nF
10nF
100pF
100pF
100pF
100nF
100nF
100pF
100pF
100pF
100pF
4.7pF
3.3pF
1.5pF
4.7pF
22pF
2.7pF
10nF
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
not equiped
replaced by R9
68nH
22nH
replaced by C16
not equiped
33nH
BFR92
BC847
RF1211B
MC33591
9.864375MHz
SMA
28 pins
1111
315MHz
Basic
OOK/FSK
1.2kbps
180k 1%
1M 1%
1k
not equiped
not equiped
not equiped
not equiped
not equiped
1k
not equiped
47k
10k
not equiped
0R
100nF
10nF
100pF
not equiped
not equiped
100nF
100nF
not equiped
100pF
not equiped
100pF
not equiped
not equiped
not equiped
not equiped
not equiped
not equiped
not equiped
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
33pF
not equiped
not equiped
not equiped
not equiped
82nH
not equiped
not equiped
BC847
not equiped
MC33591
9.864375MHz
SMA
28 pins
1120
433.92MHz
LNA+SAW
OOK/FSK
1.2kbps
1121
433.92MHz
Basic
OOK/FSK
1.2kbps
1131
868.3MHz
Basic
OOK/FSK
1.2kbps
1141
916.5MHz
Basic
OOK/FSK
1.2kbps
180k 1%
1M 1%
1k
15k
10k
1k
not equiped
1k
1k
not equiped
47k
10k
10k
not equiped
100nF
10nF
100pF
100pF
100pF
100nF
100nF
27pF
100pF
100pF
100pF
3.9pF
1.5pF
1pF
1.8pF
8.2pF
8.2pF
10nF
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
not equiped
replaced by R9
56nH
18nH
replaced by C16
not equiped
15nH
BFR92
BC847
RF1172B
MC33591
13.580625MHz
SMA
28 pins
180k 1%
1M 1%
1k
not equiped
not equiped
not equiped
not equiped
not equiped
1k
not equiped
47k
10k
not equiped
0R
100nF
10nF
100pF
not equiped
not equiped
100nF
100nF
not equiped
100pF
not equiped
100pF
not equiped
not equiped
6.8pF
not equiped
not equiped
not equiped
not equiped
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
27pF
not equiped
not equiped
not equiped
not equiped
56nH
not equiped
not equiped
BC847
not equiped
MC33591
13.580625MHz
SMA
28 pins
180k 1%
1M 1%
1k
not equiped
not equiped
not equiped
not equiped
not equiped
1k
not equiped
47k
10k
not equiped
0R
100nF
10nF
100pF
not equiped
not equiped
100nF
100nF
not equiped
100pF
not equiped
100pF
not equiped
not equiped
3.3pF
not equiped
not equiped
not equiped
not equiped
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
27pF
not equiped
not equiped
not equiped
not equiped
10nH
not equiped
not equiped
BC847
not equiped
MC33593
13.577491MHz
SMA
28 pins
180k 1%
1M 1%
1k
not equiped
not equiped
not equiped
not equiped
not equiped
1k
not equiped
47k
10k
not equiped
0R
100nF
10nF
100pF
not equiped
not equiped
100nF
100nF
not equiped
100pF
not equiped
100pF
not equiped
not equiped
6.8pF
not equiped
not equiped
not equiped
not equiped
10nF
4.7nF
100nF
470nF
390pF
10pF
10nF
not equiped
not equiped
68pF
not equiped
not equiped
not equiped
not equiped
1.5nH
not equiped
not equiped
BC847
not equiped
MC33593
14.331195MHz
SMA
28 pins
Nota : for all modules, C26=4.7nF if max data rate=1200bps. for general use, C26 is not equiped
A Receiver Using Romeo2, Rev. 0
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CAD Files
Board Geometry
Refer to the updated pinout described in “How to use the Romeo2 RF Module” on page 14.
A Receiver Using Romeo2, Rev. 0
28
Freescale Semiconductor
CAD Files
Component Placement Side 1
Refer to the updated pinout described in “How to use the Romeo2 RF Module” on page 14.
Component Placement Side 2
Refer to the updated pinout described in “How to use the Romeo2 RF Module” on page 14.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
29
CAD Files
Copper Side 1
Copper Side 2
A Receiver Using Romeo2, Rev. 0
30
Freescale Semiconductor
CAD Files
Varnish Side 1
Not available
Varnish Side 2
Not available
Silkscreen Side 1
Refer to the updated pinout described in “How to use the Romeo2 RF Module” on page 14.
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
31
CAD Files
Silkscreen Side 2
Refer to the updated pinout described in “How to use the Romeo2 RF Module” on page 14.
Drilling and Sizes
A Receiver Using Romeo2, Rev. 0
32
Freescale Semiconductor
CAD Files
A Receiver Using Romeo2, Rev. 0
Freescale Semiconductor
33
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