CMX901
RF Power Amplifier
2020 CML Microsystems Plc D/901/6
Page 1 of 16
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
Broadband Efficient RF Power Amplifier
D/901/6 April 2020 DATASHEET Provisional Information
Features
Wide operating frequency range
130MHz to 950MHz
Typical output power:
• 2.5W operating at 160MHz
• 1.8W operating at 435MHz
• 1.5W operating at 915MHz
High power gain 40dB
High power added efficiency
up to 60% at VHF
Single polarity supply voltage
2.5V to 6V
Small 28 pin WQFN package
Applications
Wireless data communications
FSK, FFSK/MSK, GFSK/GMSK, Multi-level FSK
Analogue FM handheld radio terminals
Marine AIS Class-B and Marine AIS-SART
RFID readers/writers
Automatic meter reading (AMR)
Wireless sensor networks
Mesh/Ad hoc systems
Remote control and sensing systems
Commercial and consumer communications
VGS3
VDD2
VGS2
VDD1
RFIN
RFIN
VGS1
VA
RFOUT
RFOUT
RFOUT
RFOUT
RFOUT
PA 1PA 1 PA 2 PA 3
CMX901
1 Brief Description
The CMX901 is a three stage high-gain and high efficiency RF power amplifier. The device is ideally suited for use in VHF
and UHF frequency bands up to 950MHz.
The first and second stages of the amplifier operate in a class-A and class-AB mode respectively, and the third stage
operates in a class-C mode for maximum efficiency.
External components are required to match the device input and output ports to 50 Ohms. The CMX901 is available in a
small footprint 5mm x 5mm, low thermal resistance 28-pin WQFN package making it ideal for small form factor
applications such as data modules as well as handheld radio terminals.
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 2 of 16
CONTENTS
Section Page
1 Brief Description ....................................................................................................................................................... 1
1.1 History ...................................................................................................................................................................... 3
2 Block Diagram .......................................................................................................................................................... 3
3 Performance Specification ........................................................................................................................................ 4
3.1 Electrical Performance .............................................................................................................................................. 4
3.1.1 Absolute Maximum Ratings ....................................................................................................................................... 4
3.1.2 Operating Limits ........................................................................................................................................................ 4
3.1.3 Operating Characteristics .......................................................................................................................................... 5
3.2 Typical Performance.................................................................................................................................................. 6
3.2.1 Operation at 160MHz ................................................................................................................................................ 6
3.2.2 Operation at 435MHz ................................................................................................................................................ 7
3.2.3 Operation at 915MHz ................................................................................................................................................ 8
4 Pin and Signal Definitions ......................................................................................................................................... 9
4.1 Pin List ...................................................................................................................................................................... 9
4.2 Signal Definitions .................................................................................................................................................... 10
5 Application Information ......................................................................................................................................... 11
5.1 General Description ................................................................................................................................................ 11
5.2 Main Characteristics ................................................................................................................................................ 11
5.2.1 Input Impedance ..................................................................................................................................................... 11
5.2.2 Thermal Design ....................................................................................................................................................... 12
6 General Application Schematic ............................................................................................................................... 13
7 PCB Layout ............................................................................................................................................................. 14
8 Application Notes ................................................................................................................................................... 14
8.1 Output Power Control ............................................................................................................................................. 14
8.1.1 TDMA Operation ..................................................................................................................................................... 14
9 Packaging ............................................................................................................................................................... 15
9.1 Ordering ................................................................................................................................................................. 15
Table Page
Table 1 S-parameter data (S11), VDD = 4V, Vgs1 = 1.65V, Vgs2 = 1.35V and Vgs3 = 0.93V, Ids = 18mA .......................................... 12
Table 2a Recommended External Components (variations with frequency) ............................................................................... 14
Figure Page
Figure 1 CMX901 Block Diagram ................................................................................................................................................. 3
Figure 2 Input power to output power characteristic, VDD = 4V .................................................................................................... 6
Figure 3 Variation of output power with temperature, VDD = 4V, VPARAMP = 3.3V, input level = -5dBm .................................... 6
Figure 4 Output power vs. control voltage characteristics and variation with temperature, VDD = 4V, input level = -5dBm ............. 6
Figure 5 Output power and efficiency variation with temperature, VDD = 4V, input level = -5dBm, VPARAMP = 3.3V .......................... 6
Figure 6 Input power to output power characteristic, VDD = 4V at 435MHz ................................................................................... 7
Figure 7 Variation in output power with temperature, VDD = 4V, VPARAMP = 3.3V, input level = -10dBm .......................................... 7
Figure 8 Output power vs. control voltage characteristics variation with temperature, VDD = 4V, input level = -10dBm .................. 7
Figure 9 Output power and efficiency variation with temperature, VDD = 4V, input level = -10dBm, VPARAMP = 3.3V ........................ 7
Figure 10 Input power to output power characteristic, VDD = 4V at 915MHz ................................................................................. 8
Figure 11 Variation in output power with temperature, VDD = 4V, VPARAMP = 3.3V, input level = 0dBm ........................................... 8
Figure 12 Output power vs. control voltage characteristics variation with temperature, VDD = 4V, input level = 0dBm ................... 8
Figure 13 Output power and efficiency variation with temperature, VDD = 4V, input level = 0dBm, VPARAMP = 3.3V ......................... 8
Figure 14 Pin Configuration ......................................................................................................................................................... 9
Figure 15 S11 response, VDD = 4V, Vgs1 = 1.65V, Vgs2 = 1.35V and Vgs3 = 0.93V, Ids = 18mA ........................................................ 11
Figure 16 CMX901 Recommended External Components ........................................................................................................... 13
Figure 17 QT8 Mechanical Outline ............................................................................................................................................ 15
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 3 of 16
1.1 History
Version
Date
6
22nd April 2020
5
9th August 2019
4
19th July 2017
3
9th February 2017
2
7th February 2017
1
January 2017
This is Provisional Information; changes and additions may be made to this specification. Parameters marked TBD or left
blank will be included in later issues.
2 Block Diagram
NC
NC
VGS3
NC
VDD2
VGS2
NC
1
1
VDD1
NC
RFIN
NC
RFIN
NC
NC
VGS1
NC
NC
NC
NC
VA
NC
NC
RFOUT
RFOUT
RFOUT
RFOUT
NC
RFOUT
2
3
4
5
6
7
9
10
11
12
13
14
21
20
19
18
17
16
15
28
27
26
25
24
23
22
8
PA 1PA 1 PA 2 PA 3
CMX901
Figure 1 CMX901 Block Diagram
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 4 of 16
3 Performance Specification
3.1 Electrical Performance
3.1.1 Absolute Maximum Ratings
Exceeding these maximum ratings can result in damage to the device.
Notes
Min.
Max.
Unit
Supply: VDD - VSS
1
-0.5
12.0
V
IDD - ISS
2
2.2
A
RF power at input pin
1
15
dBm
Output load VSWR
10:1
RF Power per pin
30
dBm
Notes
1. Transient and not operational i.e. Vgs1, Vgs2 and Vgs3 set to 0V
2. Rating for peak or continuous operation
QT8 Package (28-pin WQFN)
Notes
Min.
Max.
Unit
Storage Temperature
-50
+125
°C
3.1.2 Operating Limits
Correct operation of the device outside these limits is not implied.
Notes
Min.
Max.
Unit
Supply Voltage:
VDD – VSS
2.5
6
V
VGS – VSS (per stage)
2.5
V
Operating Air Temperature (TAMB)
-40
+85
°C
Maximum Allowable Junction Temperature
+125
°C
Maximum Continuous Power Dissipation (PDISS )
3, 4
1.8
W
Notes
3. Dependent on PCB layout arrangements and heatsinking, see section 5.2.2.
4. PDISS= PDC–POUT , where: PDC = VDD x IDD and POUT = measured RF output power.
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 5 of 16
3.1.3 Operating Characteristics
For the following conditions unless otherwise specified: External components as recommended in
Figure 16, VDD = 4.0V
TAMB = 25°C, VBIAS = 3.3V
Specification
Min.
Typ.
Max.
Unit
Condition
RF Frequency Range
130
-
950
MHz
Quiescent Current (from VDD)
-
-
1
µA
VBIAS = VPARAMP = 0V
Thermal Resistance RJC (junction to
central heatsink ground pad)
-
2.5
3
°C/W
3.1.3.1 Operating Characteristics 160MHz
RF frequency = 160MHz, RF power input = -5dBm, VPARAMP = 3.3V
Specification
Min.
Typ.
Max.
Unit
Condition
Maximum output power (Pmax160)
-
2.5
-
W
Pin = -5dBm
Power added efficiency
-
61
-
%
Pout = 2.5W, VDD = 4V
Input power for Pmax160
-
-5
-
dBm
VDD = 4V
Gain
-
-
39
45
-
-
dB
dB
Pin = -5dBm
Pin = -15dBm
Second harmonic
-
-23
-
dBc
Pmax 160
Third harmonic
-
-37
-
dBc
Pmax 160
Fourth harmonic
-
-54
-
dBc
Pmax 160
Other non-harmonic spurious
-
-
-75
dBc
Pmax 160
Input VSWR
-
See s11
data
-
See section 5.2.1
Stability, VSWR 5:1
Stable all phases, continuous or
pulsed operation, power output
variation with load phase +1,-4 dB
(typ.)
Variation from normal
output power with 50Ω
load and with input power
(Pin) between -15 dBm and
0 dBm.
Open circuit, Short circuit
No
damage
Continuous operation for
30 seconds
3.1.3.2 Operating Characteristics 435MHz
RF frequency = 435MHz, RF power input = -10dBm, VPARAMP = 3.3V
Specification
Min.
Typ.
Max.
Unit
Condition
Maximum output power (Pmax435)
-
1.8
-
W
Pin = -5dBm
Power added efficiency
-
52
-
%
Pout = 1.8W, VDD = 4V
Input power for Pmax435
-
-10
-
dBm
VDD = 4V
Gain
-
42.5
-
dB
ACPR
-
-
-70
dBc
EN 300 086, 25kHz
channel
Reverse Isolation
-
-60
-
dB
Pmax 435
Second harmonic
-
-30
-
dBc
Pmax 435
Third harmonic
-
-52
-
dBc
Pmax 435
Fourth harmonic
-
-46
-
dBc
Pmax 435
Other non-harmonic spurious
-
-
-75
dBc
Pmax 435
Input VSWR
-
See s11
data
-
See section 5.2.1
Stability, VSWR 5:1
Stable all phases, continuous
operation, power output
variation with load phase ±2dB
(typ.)
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 6 of 16
Open circuit, Short circuit
No damage
Continuous operation
for 30 seconds
3.1.3.3 Operating Characteristics 915MHz
RF frequency = 915MHz, RF power input = 0dBm, VPARAMP = 3.3V
Specification
Min.
Typ.
Max.
Unit
Condition
Maximum output power (Pmax915)
-
1.5
-
W
VDD = 4V
Power added efficiency
-
42
-
%
Pout = 1.5W, VDD = 4V
Input power for Pmax915
-
0
-
dBm
Gain
-
-
32
31
-
-
dB
dB
Pin = 0 dBm
Pin = -10 dBm
Second harmonic
-
-45
-
dBc
Pmax915
Third harmonic
-
-54
-
dBc
Pmax915
Fourth harmonic
-
-52
-
dBc
Pmax915
Other non-harmonic spurious
-
-
-75
dBc
Pmax915
Input VSWR
-
See s11
data
-
Stability, VSWR 3:1
Stable all phases, continuous
operation, power output variation
with load phase ±2 dB (typ.)
Stability, VSWR 10:1
Stable all phases
Open circuit, Short circuit
No damage
Continuous operation for 30s
3.2 Typical Performance
3.2.1 Operation at 160MHz
Performance data measured using EV9011 PCB, circuit values as Table 2 / Figure 16.
Figure 2 Input power to output power characteristic,
VDD = 4V
Figure 3 Variation of output power with temperature,
VDD = 4V, VPARAMP = 3.3V, input level = -5dBm
Figure 4 Output power vs. control voltage
characteristics and variation with temperature,
VDD = 4V, input level = -5dBm
Figure 5 Output power and efficiency variation with
temperature, VDD = 4V, input level = -5dBm, VPARAMP = 3.3V
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 7 of 16
3.2.2 Operation at 435MHz
Performance data measured using EV9011 PCB, circuit values as Table 2 / Figure 16.
Figure 6 Input power to output power characteristic,
VDD = 4V at 435MHz
Figure 7 Variation in output power with temperature,
VDD = 4V, VPARAMP = 3.3V, input level = -10dBm
Figure 8 Output power vs. control voltage characteristics
variation with temperature, VDD = 4V,
input level = -10dBm
Figure 9 Output power and efficiency variation with
temperature, VDD = 4V, input level = -10dBm,
VPARAMP = 3.3V
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 8 of 16
3.2.3 Operation at 915MHz
Performance data measured using EV9011 PCB, circuit values as Table 2 / Figure 16.
Figure 10 Input power to output power characteristic,
VDD = 4V at 915MHz
Figure 11 Variation in output power with temperature,
VDD = 4V, VPARAMP = 3.3V, input level = 0dBm
Figure 12 Output power vs. control voltage characteristics
variation with temperature, VDD = 4V, input level = 0dBm
Figure 13 Output power and efficiency variation with
temperature, VDD = 4V, input level = 0dBm, VPARAMP = 3.3V
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 9 of 16
4 Pin and Signal Definitions
1
2
3
4
5
6
7
28
27
26
25
24
23
22
21
20
19
18
17
16
15
8
9
10
11
12
13
14
VDD1
NC
RFIN
NC
RFIN
NC
NC
VGS1
NC
NC
NC
NC
VA
NC
NC
RFOUT
RFOUT
RFOUT
RFOUT
GND
NC
NC
NC
VGS3
NC
VDD2
VGS2
NC
Exposed Metal Pad
RFOUT
Top View
Figure 14 Pin Configuration
4.1 Pin List
Pin No.
Pin Name
Type
Description
1
VDD1
PWR
Power supply for the first stage
2
NC
NC
Connect to GND
3
RFIN
IP
RF signal input (off-chip DC blocking capacitor required)
4
NC
NC
Connect to ground
5
RFIN
IP
As pin 3
6
NC
NC
Connect to GND
7
NC
NC
Connect to GND
8
VGS1
IP
Bias input for first stage
9
NC
NC
Connect to GND
10
NC
NC
Connect to GND
11
NC
NC
Connect to GND
12
NC
NC
Connect to GND
13
NC
NC
Connect to GND
14
VA
PWR
Connect to 3.3V
15
NC
NC
Connect to GND
16
RFOUT
OP
Power supply and RF output
17
RFOUT
18
RFOUT
19
RFOUT
20
RFOUT
21
NC
NC
Connect to GND
22
NC
NC
Connect to GND
23
NC
NC
Connect to GND
24
VGS3
IP
Bias input for output stage
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 10 of 16
Pin No.
Pin Name
Type
Description
25
NC
NC
Connect to GND
26
VDD2
PWR
Power supply for second stage
27
NC
NC
Connect to GND
28
VGS2
IP
Bias input for second stage
Exposed Metal
Pad
GND
PWR
The central metal pad must be connected to ground.
Notes:
OP = Output PWR = Power Connection
IP = Input NC = No internal connection
4.2 Signal Definitions
Signal
Name
Pins
Usage
VDD
VDD
Power supply
VGS1
VGS1
Bias input for the first amplifier stage
VGS2
VGS2
Bias input for the second amplifier stage
VGS3
VGS3
Bias input for the third amplifier stage
VPARAMP
N/A
Combined control voltage with VGS1 VGS2 configured as
Figure 16 (NB: see also section 8.1).
VBIAS
N/A
Combined control voltage VGS3 and pin VA, configured as
Figure 16.
Vss
GND
Ground
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 11 of 16
5 Application Information
5.1 General Description
The CMX901 is a three-stage RF power amplifier producing high gain at full output power. An input power of up to 0dBm
is required to achieve fully-saturated output power (0dBm at maximum operating frequency). The device requires only a
single positive power supply. The primary ground connection is via a large central pad on the bottom of the package.
.
The first and second stages of the amplifier operate in class-A and class-AB mode, respectively. The final stage operates in
Class-C mode. DC current will increase with RF input signal. The optimum load for maximum output power and efficiency
is approximately 5Ω. An external matching network is required to match this impedance to a 50Ω load (see Figure 16).
The RFIN pins are DC biased, thus a blocking capacitor is recommended between signal source and the input pins.
Vdd1 and Vdd2 provide DC power supply to the first and second stages, respectively. An RF tuning inductor is needed for
each pin. Vgs1, Vgs2 and Vgs3 should be set to different bias voltages for maximum output power and efficiency; see
Figure 16 and section 8.1 for further details.
5.2 Main Characteristics
5.2.1 Input Impedance
Typical CMX901 input impedance (S11) is shown in Figure 15 as measured with EV9011 configured for 435MHz operation
with a RC network of 470R and 1nF (but no other matching) at the input. The measured S11 response varies with inter-
stage and output matching configuration. The configuration used for this measurement was the 435MHz circuit values
from Figure 16 / Table 2.
Figure 15 S11 response, VDD = 4V, Vgs1 = 1.65V, Vgs2 = 1.35V and Vgs3 = 0.93V, Ids = 18mA
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 12 of 16
Frequency (MHz)
S(1,1) Mag ∠Ang
100
0.796 ∠- 9.537°
150
0.805 ∠- 13.911°
200
0.811 ∠- 18.941°
250
0.825 ∠- 24.26°
300
0.843 ∠- 30.397°
350
0.872 ∠- 38.211°
400
0.859 ∠- 50.154°
450
0.822 ∠- 55.754°
500
0.809 ∠- 63.538°
550
0.747 ∠- 72.205°
600
0.683 ∠- 76.943°
650
0.641 ∠- 80.317°
700
0.628 ∠- 82.409°
750
0.633 ∠- 85.03°
800
0.647 ∠- 89.029°
850
0.657 ∠- 93.691°
900
0.665 ∠- 98.609°
950
0.668 ∠- 103.614°
1000
0.671 ∠- 107.921°
Table 1 S-parameter data (S11), VDD = 4V, Vgs1 = 1.65V, Vgs2 = 1.35V and Vgs3 = 0.93V, Ids = 18mA
5.2.2 Thermal Design
The large central pad on the bottom of the package should be electrically and thermally connected to the PCB ground
plane, typically with 20-25 vias, a 0.2mm hole size is recommended and the vias must be from top layer to bottom layer.
A typical solution is a via pattern based on an inner via diameter of 0.200mm (0.025mm plating of via walls), with 25 vias
on a 0.670mm grid pattern; the vias do not need to be filled. The PCB layout should provide a thermal radiator
appropriate for the intended operation/duty cycle in order to avoid an excessive junction temperature.
It should be noted that the peak power dissipation may exceed the maximum rated continuous power dissipation (PDISS )
when the transmitter is used for discontinuous transmission for example in TDMA transmission systems. In this case
average power dissipation should not exceed PDISS.
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 13 of 16
6 General Application Schematic
1
2
3
4
5
6
7
28
27
26
25
24
23
22
21
20
19
18
17
16
15
8
9
10
11
12
13
14
GND
C24
L5
C11
RFOUT
C8
L4
C9
C21
RFIN
GND
GND
L2 L1 L3
C3C2
GND
C5C4
GND
C7C6
GND
VDD
C1
GND
R1
C20
C22
R3
C23
C12C10
R8
R7
R10 C26
R2
GND
VPARAMP
VDD1
NC
RFIN
NC
RFIN
NC
NC
VGS1
NC
NC
NC
NC
VA
NC
NC
RFOUT
RFOUT
RFOUT
RFOUT
NC
NC
NC
VGS3
NC
VDD2
VGS2
NC
Exposed
Metal Pad
RFOUT
Vgs1
Vgs1
R5
R9
GND
Vgs2
R6
R11
GND
Vgs3
Vgs2
Vbias
Vgs3
C25 C19
Figure 16 CMX901 Recommended External Components
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 14 of 16
Frequency
(MHz)
L1
(0603CS)
(nH)
L2
(0603CS)
(nH)
L3
(nH)
L4
(0630CS)
(nH)
L5
(nH)
C21
(pF)
C22
(pF)
C10
(pF)
C11
(pF)
C12
(pF)
160
56
56
19
150
12
-
3.3
12
56
5.6
435
27
27
16
43
3.6
5.6
-
4.7
-
18
915
5.6
8.7
6
10
1.8
4.7
-
10
4.7
-
Table 2a Recommended External Components (variations with frequency)
R1
N/F
C1
4.7µF
C19
100pF
R2
N/F (Note 4)
C2
Note 1
C20
N/F
R3
680 (Note 2)
C3
1uF
C21
Table 2a
R5
68k
C4
Note 1
C22
Table 2a
R6
100k
C5
1uF
C23
1nF
R7
68k
C6
Note 1
C24
Note 1
R8
51R
C7
1uF
C25
10nF
R9
47k
C8
Note 1
C26
10nF
R10
68kΩ
C9
Note 1
R11
39kΩ
C10
Table 2a
C11
Table 2a
C12
Table 2a
Notes:
1. 470pF but use 47pF at 915MHz
2. 470 recommended at 450MHz
3. All inductors are Coilcraft (www.coilcraft.com)
4. 200 recommended at 160MHz
Table 2b Recommended External Components (common values)
7 PCB Layout
Careful layout of the PCB is essential for best performance. Recommended layout may be taken from evaluation kit
EV9011.
8 Application Notes
8.1 Output Power Control
The output power of the CMX901 can be controlled by varying VPARAMP from 0V to 3.3V. This in turn adjusts VGS1 and VGS2.
It is recommended to connect VGS3, along with VA (pin 14), to 3.3V dc. This gives a satisfactory power control
characteristic for TDMA systems like DMR (ETSI standards EN 300 113 and TS 102 361).
8.1.1 TDMA Operation
Careful assessment of device stability is advised during power ramping when operating into non-50Ω loads, especially at
operating frequencies of 400MHz and above.
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 15 of 16
9 Packaging
Figure 17 QT8 Mechanical Outline of 28-pin WQFN (QT8)
9.1 Ordering
Order as Part No. CMX901 QT8
RF Power Amplifier CMX901
2020 CML Microsystems Plc D/901/6
Page 16 of 16
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.
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