WikiSysop: Created page with "==Summary== Two devices were under review for the power amplifier for this project. The project specification calls for a 5W, 50O output over the frequency range of 144-148MHz..."

2015-08-08T01:56:17Z

Created page with "==Summary== Two devices were under review for the power amplifier for this project. The project specification calls for a 5W, 50O output over the frequency range of 144-148MHz..."

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==Summary==
Two devices were under review for the power amplifier for this project. The project specification calls for a 5W, 50O output over the frequency range of 144-148MHz. One method was to design a power amplifier using discrete RF MOSFETs. The second method was to use a power amplifier module manufactured by Mitsubishi, which integrates input/output matching. I was able to find an application note by STMicroelectronics for the PD54008 and PD84001 devices, covering the frequency range of 135-175MHz.<ref>STMicroelectronics, "2 stages RF power amp: PD84001-E + PD54008L-E + LPF N-Channel
Enhancement-Mode Lateral MOSFETs," April 2007. [Online]. Available:
http://www.rell.com/resources/RellDocuments/SYS_14/ab-54008l-175.pdf. [Accessed 5 February
2012].</ref> The application note included full schematics, board layout, and test data for the complete amplifier. From the provided schematics, I designed a PCB for the ST amplifier, and did a cost comparison against the Mitsubishi amplifier module.

==STMicroelectronics Amplifier==
[[File:ST_PA_Sch.png|thumb|right|Figure 1: Schematic for the ST Power Amplifier Test Board.]]
[[File:ST_PA_Brd.png|thumb|right|Figure 2: PCB Layout for the ST Power Amplifier Test Board.]]

The PD54008 is an N-channel RF MOSFET capable of outputting 8W with 11.5dB gain at 500MHz.<ref>STMicroelectronics, "PD54008-E RF power transistor, LdmoST plastic family N-channel
enhancement-mode, lateral MOSFETs," May 2011. [Online]. Available:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/
CD00103331.pdf. [Accessed 5 February 2012].</ref> The PD84001 is an N-channel RF MOSFET capable of outputting 1W with 15dB of gain at 870MHz.<ref>STMicroelectronics, "PD84001 RF power transistor the LdmoST plastic family," August 2008.
[Online]. Available:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/
CD00147015.pdf. [Accessed 5 February 2012].</ref> The test board provides all necessary matching, DC biasing, and output filtering. The schematic for this test board is shown in Figure 1, and the board is shown in Figure 2.

===Bill of Materials===
{| border="1"
|style="text-align:center;" |'''Part'''
|style="text-align:center;" |'''Quantity'''
|style="text-align:center;" |'''Unit Cost'''
|style="text-align:center;" |'''Total Cost'''
|style="text-align:center;" |'''Source'''
|-

|PD54008
|1
|style="text-align:right;" |$7.50
|style="text-align:right;" |$7.50
|[http://search.digikey.com/us/en/products/PD54008-E/497-5296-5-ND/1144677 Digi-Key]
|-

|PD84001
|1
|style="text-align:right;" |$3.19
|style="text-align:right;" |$3.19
|[http://search.digikey.com/us/en/products/PD84001/497-8294-1-ND/1852327 Digi-Key]
|-

|SMA Male Connector
|2/5
|style="text-align:right;" |$2.51
|style="text-align:right;" |$1.00
|[http://www.dealextreme.com/p/sma-1-5-diy-connector-plug-5-pack-5132 Dealextreme]
|-

|0603 Capacitor
|23
|style="text-align:right;" |$0.0096
|style="text-align:right;" |$0.22
|[http://myworld.ebay.com/mib_instruments eBay - mib_instruments]
|-

|0603 Resistor
|6
|style="text-align:right;" |$0.00294
|style="text-align:right;" |$0.02
|[http://myworld.ebay.com/mib_instruments eBay - mib_instruments]
|-

|0603HC-18NX
|1
|style="text-align:right;" |$0.79
|style="text-align:right;" |$0.79
|[http://www.coilcraft.com/0603hc.cfm Coilcraft]
|-

|1008CS-xxxX
|3
|style="text-align:right;" |$0.79
|style="text-align:right;" |$2.37
|[http://www.coilcraft.com/1008CS.cfm Coilcraft]
|-

|1812SMS-22N
|2
|style="text-align:right;" |$0.95
|style="text-align:right;" |$1.90
|[http://www.coilcraft.com/midi.cfm Coilcraft]
|-

|A05T
|1
|style="text-align:right;" |$0.91
|style="text-align:right;" |$0.91
|[http://www.coilcraft.com/mini.cfm Coilcraft]
|-

|Male Header
|5
|style="text-align:right;" |$0.01
|style="text-align:right;" |$0.05
|[http://www.ebay.com/ eBay]
|-

|PCB
|2.075"x0.875"/3
|style="text-align:right;" |$5.00
|style="text-align:right;" |$3.03
|[http://dorkbotpdx.org/wiki/pcb_order Laen's PCB]
|-

|'''Total Unit Cost'''
|
|
|style="text-align:right;" |'''$28.38'''
|
|-
|}

==Mitsubishi Amplifier==
[[File:Mitsubishi_PA_Sch.png|thumb|right|Figure 3: Schematic for the Mitsubishi Power Amplifier Test Board.]]
[[File:Mitsubishi_PA_Brd.png|thumb|right|Figure 4: PCB Layout for the Mitsubishi Power Amplifier Test Board.]]

The RA07M1317M MOSFET amplifier module is a two-stage amplifier capable of outputting 6.5W with approximately 35dB gain, internally matched to 50O over the frequency range of 135-175MHz.<ref>Mitsubishi Electric, "RA07M1317M 135-175MHz 6.5W 7.2V, 2 Stage Amp. For Portable Radio," 30
June 2010. [Online]. Available: http://www.mitsubishielectric-mesh.com/products/pdf/ra07m1317m.pdf. [Accessed 5 February 2012].</ref> The test board provides two SMA connectors and bypassing capacitors for the gate and drain voltage inputs to the module. The schematic for this test board is shown in Figure 3, and the board is shown in Figure 4.

The schematic, board, and Gerber files can be downloaded here: http://rev0proto.com/files/ra07m1317m_v10.zip

===Testing===
The amplifier was tested using an HP 8922M GSM Test Set, using the Aux. RF Out supplying 0-9dBm at 144-148MHz to the RF IN port of the amplifier, and reading the RF OUT power through the RF In/Out port on the Test Set. VDD was supplied at 6-8.4V through an HP 6284A power supply. VGG was supplied at 0-3.5V using a power supply and potentiometer. Gate voltage was monitored using an HP 3466A multimeter, and current was read using the built-in meter of the 6284A.

<gallery perrow=1 widths=400px heights=240px>
File:Pout_Gain_Efficiency_vs_Vgg_at_Vdd_7.4V.PNG|Pout, Gain and Efficiency vs. VGG at VDD = 7.4V
File:Pout_vs_Vgg_at_Vdd_6_7.4_8.4V.PNG|Pout vs. VGG at VDD = 6, 7.4, 8.4V
File:Pin_vs_Vdd_for_Pout_5W.PNG|Input power for 5W output varying VDD from 6-8.4V
</gallery>

Using the data for constant 5W output power at varying drain voltage in conjunction with the measured output powers of the ADF7012 or TH7122 will allow constant RF output power as the battery voltage decreases, as measured by the microcontroller. Varying the gate voltage provides a means of changing output power, at the expense of decreased efficiency at lower powers. At a gate voltage of 0V, the device only draws 7uA at 8.4V, effectively shutting off the device and allowing for a constant connection to the battery.

===Bill of Materials===
{| border="1"
|style="text-align:center;" |'''Part'''
|style="text-align:center;" |'''Quantity'''
|style="text-align:center;" |'''Unit Cost'''
|style="text-align:center;" |'''Total Cost'''
|style="text-align:center;" |'''Source'''
|-

|RA07M1317M
|1
|style="text-align:right;" |$19.95
|style="text-align:right;" |$19.95
|[http://www.rfparts.com/module_sau-sav.html RFParts]
|-

|SMA Male Connector
|2/5
|style="text-align:right;" |$2.51
|style="text-align:right;" |$1.00
|[http://www.dealextreme.com/p/sma-1-5-diy-connector-plug-5-pack-5132 Dealextreme]
|-

|0603 4.7uF Capacitor
|2
|style="text-align:right;" |$0.0096
|style="text-align:right;" |$0.02
|[http://myworld.ebay.com/mib_instruments eBay - mib_instruments]
|-

|3216 22uF Tantalum Capacitor
|2
|style="text-align:right;" |$0.64
|style="text-align:right;" |$1.28
|[http://search.digikey.com/us/en/products/TAJB226K016RNJ/478-1682-1-ND/564714 Digi-Key]
|-

|Male Header
|3
|style="text-align:right;" |$0.01
|style="text-align:right;" |$0.03
|[http://www.ebay.com/ eBay]
|-

|PCB
|1.35"x0.95"/3
|style="text-align:right;" |$5.00
|style="text-align:right;" |$2.14
|[http://dorkbotpdx.org/wiki/pcb_order Laen's PCB]
|-

|'''Total Unit Cost'''
|
|
|style="text-align:right;" |'''$24.42'''
|
|-
|}

===PCB/Construction Photos===
<gallery perrow=3 widths=240px heights=120px>
File:PA_PCB_Bottom.jpg|Bottom of unpopulated PCB
File:PA_PCB_Top.jpg|Top of unpopulated PCB
File:PA_Top.jpg|Populated PCB and mounted heatsink
</gallery>

==Cost Comparison==
From the bills of materials above, you can see the price breakdown for the two amplifiers. While the ST amplifier has a lower cost per module (at a quantity of 3 boards or greater), the price between the two is small, and when factoring in labor, the Mitsubishi amplifier has a lower overall cost. Given that the figure for labor given in this table only includes the labor for designing the PCB, it is clear that the simpler Mitsubishi design would save more time and effort in assembly, test, and debug, given the short timeline of this project.

==References==
<references/>

Power Amplifier - Revision history

WikiSysop: Created page with "==Summary== Two devices were under review for the power amplifier for this project. The project specification calls for a 5W, 50O output over the frequency range of 144-148MHz..."