CML Microcircuits
dPMR RF Demonstrator
August 2009
Product Preview
A Compact Low-cost RF Technology Demonstrator for Design and Development
of Digital FDMA PMR Transceiver Products
Low cost dPMR/PMR446 technology
On-board 19.2MHz reference and
PLL/VCOs for 446MHz operation
Meets EN 301 166 (dPMR) and EN 300 296
DE6181 (CMX7141) Interfacing and
PE0002 control via PC
446.0 to 446.2 MHz at 500mW Tx operation
Compact footprint:
RF area = 45mm x 50mm
Sensitive switched bandwidth limiterdiscriminator receiver
Functional test scripts available
Brief Description
The ATB010 is a small, low cost, PCB-based RF technology demonstrator aimed at speeding
manufacturers' design and development of dPMR/PMR446 transceiver products. The board is designed
as a plug-in to the CML *DE6181 demonstration kit. Along with a *PE0002 host controller a full RF
transceiver can be assembled to offer a variety of voice and data options configurable via Function
Image™ and control scripts.
All the necessary RF circuits are provided on the ATB010 PCB: receiver and transmitter VCOs, a
500mW RF power amplifier, harmonic filter, antenna switching, LNA, RF to IF mixer and limiter
discriminator IF processing. The RF performance is designed to be compliant with EN 301 166 (6.25kHz
dPMR) and EN 300 296 (12.5kHz PMR446). The DE6181 demonstration kit is a flexible platform that
can provide both digital (dPMR) and analogue (PMR446) functionality.
The design is production-engineered for low bill of materials cost, with a minimum number of component
types and values and uses only low-cost off-the-shelf components. The design uses a single 3.6V
supply, e.g. 3 AAA cells or a Li-ion battery.
*DE6181: Demonstration Kit for CML’s CMX618 and CMX7141.
*PE0002: Evaluation Kit - a global interface system for use with evaluation kits for CML's new generation
ICs, including FirmASIC®-based products.
© 2009 CML Microsystems Plc
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ATB010 – dPMR RF Demonstrator
CML Microcircuits
Rx Section
Image Filter
Xtal Filter
(Fc = 45MHz)
LO 1
LO 2
Tx Section
The ATB010 functional block diagram
On-board Circuits
Front end LNA
A UHF discrete bipolar LNA. Along with subsequent stages, this is biased to achieve the demanding
receiver intermodulation requirements.
SAW image filter
This filter (after the LNA) is an 8MHz bandwidth 446MHz SAW filter providing rejection of image and
other spurious responses.
After approximately 2dB of attenuation, a diode ring mixer is used to convert from 446MHz to the 1st IF
of 45MHz. This requires approximately +4dBm LO drive.
Post mixer IF amplifier
An isolation amplifier that provides a good match at its output to the crystal filter. The input from the
mixer is matched by a Pi network giving a good 50Ohm match.
IF crystal filter
A 4-pole, fundamental mode, 2 x UM1 packaged crystal filter with a passband of approximately
+/-3.75kHz. Correct matching of the filters is necessary to achieving optimum performance.
Post filter amplifier
A resistive termination to the FM IF IC input. It also provides a high input impedance to the crystal filter
output matching network. The gain provided overcomes the losses in not matching to the high
impedance of the FM IF IC input.
© 2009 CML Microsystems Plc
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CML Microcircuits
Receiver local oscillators
VCOs are provided for 1st and 2nd LOs of the receiver, both locked using a dual PLL synthesiser IC.
The 1st LO in particular requires excellent performance in order for the receiver to meet the required
adjacent channel rejection at 6.25kHz offset.
The 2nd local oscillator at 44.545MHz is provided using a conventional common collector Collpits circuit.
The PLL reference used is 5kHz in this case.
Reference oscillator
A 1.5ppm 19.2MHz VCTCXO is provided on the PCB. Note that for transmit operation, both the VCO
and the reference frequencies are modulated.
2nd IF/demodulation
The IF signal from the post crystal filter amplifier is presented to the input of the FM/IF demodulation IC.
This IC and surrounding circuitry provide a number of functions:
A mixer from the 1st IF to 455kHz (the 2nd IF)
Further channel filtering using inexpensive ceramic filters which are selectable for 12.5kHz or
6.25kHz operation)
A limiter-discriminator demodulator using a ceramic resonator
Switched loading on the discriminator to provide a consistent output across both operating
channel bandwidths
An RSSI output that can be monitored by a CMX7141 AUX ADC.
The transmit VCO operates at the final operating frequency and uses the same oscillator architecture as
the receive VCO.
A separate varactor diode is used for applying modulation from MOD1. The VCO is locked using the RF
PLL, which requires reprogramming between receiver and transmitter operation. A common loop filter is
used for both the Tx and Rx VCOs.
The transmitter provides at least +28dBm over the range 440 to 450 MHz.
The CMX7141 RAM DAC output is connected to the PA control line via a diode and transistor to provide
sufficient current to the PA control pins.
Tx/Rx switch
Circuitry is provided to implement a classical series-shunt Tx/Rx switch using PIN diodes after a lumped
quarter wave section. The diodes are activated in transmit via the TxEN signal from the CMX7141. An
additional diode is provided to protect the LNA from extremely strong signals (e.g. a nearby transceiver).
This branch of the switch then goes the receiver LNA input.
Harmonic filter
A low-loss low pass filter with traps centred at the 2nd and 3rd Tx harmonics. This filter is common to the
transmitter and receiver paths and is connected between the Tx/Rx switch and the antenna connector
Power detector
An RF power detector operates on the forward branch of the discrete directional coupler. The output
from the detector can be monitored using AUX ADC3 on the CMX7141 of the EV6181. Alternatively it
can be monitored via an on-board test point.
© 2009 CML Microsystems Plc
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ATB010 – dPMR RF Demonstrator
CML Microcircuits
Voice Input from Microphone
Audio Output to Loudspeaker/Earphone
DE6181 DemoKit
PE0002 DemoKit Interface Card
CMX7141 dPMR Baseband Processor
CMX618 RALCWI Vocoder with Integrated Voice Codec
32-bit RISC DSP Microprocessor
USB to/from PC
To Rx Antenna
Tx Dummy Load
Antenna Connector
The ATB010 RF Demonstrator configured as a complete dPMR transceiver
Example Performance Specification
Frequency range
446.0 to 446.2 MHz
Channel spacing
6.25 or 12.5 kHz
Transmitter output power
4-Level FSK and analogue FM
Sensitivity (BER = 1%)
-118dBm (typ)
Adjacent channel power
Adjacent channel rejection
Power supply
3.6V (nom)
© 2009 CML Microsystems Plc
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CML Microcircuits
Application Concerns
The ATB010 itself is a demonstration PCB and has not been approved to any product standards.
The user is advised not to radiate signals using the ATB010 without complying with the local regulatory
requirements, for example obtaining a test and development licence from the appropriate national body.
Note: Tests can be performed using the ATB010 using cable connection and dummy loads without the
need for radiated signals.
In the laboratory environment leakage from cables is often sufficient for the sensitive ATB010 receiver to
This product is designed and manufactured by Applied Technology, a member of the CML Microsystems
Plc group of companies.
For more information, please contact:
[email protected]
Telephone: +44 (0) 1749 881130
Fax: +44 (0) 1749 881133
© 2009 CML Microsystems Plc
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CML Microcircuits
Handling precautions: This product includes input protection, however, precautions should be taken to prevent device damage
from electro-static discharge. CML does not assume any responsibility for the use of any circuitry described. No IPR or circuit
patent licences are implied. CML reserves the right at any time without notice to change the said circuitry and this product
specification. CML has a policy of testing every product shipped using calibrated test equipment to ensure compliance with this
product specification. Specific testing of all circuit parameters is not necessarily performed.
© 2009 CML Microsystems Plc
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August 2009