WikiSysop: Created page with "{{navup |previous=SNA |up=Spectrum_Analyzer |next=SA_LO1}} This page describes the input/TG low-pass filter for the DIY Spectrum Analyzer. ==Summary== File:Rev0VTx_VCO_Sc..."

2016-01-21T02:20:40Z

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This page describes the input/TG low-pass filter for the DIY Spectrum Analyzer.

==Summary==
[[File:Rev0VTx_VCO_Sch.png|thumb|right|Schematic for the input LPF.]]

The input must be low-pass filtered to allow only the desired passband of 30MHz-2.5GHz through to the rest of the system. Likewise, the tracking generator must have an output low-pass filter to prevent LO and IF feedthrough at 3.5-6GHz. The low-pass filter is a 7-pole Chebyshev lumped element design, chosen for its performance, size, and simplicity. The filter has a -3dB bandwidth of 2.57GHz, with 50dB of rejection at the 1st IF of 3.5GHz, and >50dB rejection through 8.5GHz.

==Testing==
* '''8.6.2013''': The filter was designed and simulated in Qucs using S2P part definitions from Murata's SimSurfing utility. Results of the simulation are shown below.

{| border="1"
|'''Frequency (MHz)'''
|'''Power (dBm)'''
|-

|150
|align="right" | -0.06
|-

|200
|align="right" | -0.02
|-

|250
|align="right" | -0.03
|-

|300
|align="right" | -0.07
|-

|350
|align="right" | -0.06
|-

|400
|align="right" | 0.03
|-

|450
|align="right" | 0.04
|-

|500
|align="right" | 0.02
|-

|550
|align="right" | -0.07
|-

|600
|align="right" | -0.07
|-

|650
|align="right" | 0.05
|-

|700
|align="right" | 0.09
|-

|750
|align="right" | -0.05
|-

|800
|align="right" | -0.03
|-

|850
|align="right" | 0.02
|-

|900
|align="right" | 0.00
|-

|950
|align="right" | -0.07
|-

|1000
|align="right" | -0.10
|-

|1500
|align="right" | -0.17
|-

|2000
|align="right" | 0.21
|-

|2500
|align="right" | 0.04
|-

|3000
|align="right" | 0.62
|-

|3500
|align="right" | 1.72
|-

|4000
|align="right" | 1.47
|}

==Revisions==
* '''1.0''': Initial revision.

==Bill of Materials (v1.0)==
{| 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'''
|-

|ADF4350
|1
|style="text-align:right;" |$12.02
|style="text-align:right;" |$12.02
|[http://www.digikey.com/product-detail/en/ADF4350BCPZ/ADF4350BCPZ-ND/1999320 Digi-Key]
|-

|FOX924B-10.000
|1
|style="text-align:right;" |$3.76
|style="text-align:right;" |$3.76
|[http://www.digikey.com/product-detail/en/FOX924B-10.000/631-1067-1-ND/1024772 Digi-Key]
|-

|ADP124
|1
|style="text-align:right;" |$1.95
|style="text-align:right;" |$1.95
|[http://www.digikey.com/product-detail/en/ADP124ARHZ-3.3-R7/ADP124ARHZ-3.3-R7CT-ND/2237789 Digi-Key]
|-

|AP1115
|1
|style="text-align:right;" |$0.54
|style="text-align:right;" |$0.54
|[http://www.digikey.com/product-detail/en/AP1115BY35L-13/AP1115BY35LDICT-ND/1301510 Digi-Key]
|-

|MSP430G2553
|1
|style="text-align:right;" |$2.58
|style="text-align:right;" |$2.58
|[http://www.digikey.com/product-detail/en/MSP430G2553IPW20R/296-28430-1-ND/2638889 Digi-Key]
|-

|0402 100nF Capacitor
|10
|style="text-align:right;" |$0.011
|style="text-align:right;" |$0.11
|[http://www.digikey.com/product-detail/en/C1005X5R1A104K050BA/445-1265-1-ND/567732 Digi-Key]
|-

|0402 10pF Capacitor
|10
|style="text-align:right;" |$0.0116
|style="text-align:right;" |$0.12
|[http://www.digikey.com/product-detail/en/C1005C0G1H100D050BA/445-1235-1-ND/567743 Digi-Key]
|-

|0603 Capacitor
|9
|style="text-align:right;" |$0.0096
|style="text-align:right;" |$0.09
|[http://myworld.ebay.com/mib_instruments eBay - mib_instruments]
|-

|0603 4.7uF Capacitor
|3
|style="text-align:right;" |$0.1484
|style="text-align:right;" |$0.45
|[http://www.digikey.com/product-detail/en/CL10A475MO8NNNC/1276-1904-1-ND/3889990 Digi-Key]
|-

|0805 10uF Capacitor
|1
|style="text-align:right;" |$0.30
|style="text-align:right;" |$0.30
|[http://www.digikey.com/product-detail/en/C1210X104KCRACTU/399-6769-1-ND/3083943 Digi-Key]
|-

|0603 Resistor
|10
|style="text-align:right;" |$0.00294
|style="text-align:right;" |$0.03
|[http://myworld.ebay.com/mib_instruments eBay - mib_instruments]
|-

|0603 Green LED
|1
|style="text-align:right;" |$0.10
|style="text-align:right;" |$0.10
|[http://search.digikey.com/us/en/products/LG%20Q971-KN-1/475-1409-1-ND/1802597 Digi-Key]
|-

|0603 Red LED
|1
|style="text-align:right;" |$0.27
|style="text-align:right;" |$0.27
|[http://search.digikey.com/us/en/products/LS%20Q976-NR-1/475-2512-1-ND/1802639 Digi-Key]
|-

|0603 Ferrite Bead (470 Ohm)
|2
|style="text-align:right;" |$0.0472
|style="text-align:right;" |$0.09
|[http://www.digikey.com/product-detail/en/MPZ1608S471A/445-5222-1-ND/2117956 Digi-Key]
|-

|Male Header
|8
|style="text-align:right;" |$0.01
|style="text-align:right;" |$0.03
|[http://www.ebay.com/ eBay]
|-

|SMA Female Connector
|4
|style="text-align:right;" |$3.37
|style="text-align:right;" |$13.48
|[http://www.digikey.com/product-detail/en/CONSMA003.062/CONSMA003.062-ND/1577208 Digi-Key]
|-

|PCB
|1.75"x1.1"/3
|style="text-align:right;" |$10.00
|style="text-align:right;" |$6.42
|[http://dorkbotpdx.org/wiki/pcb_order Laen's PCB]
|-

|'''Total Unit Cost'''
|
|
|style="text-align:right;" |'''$42.32'''
|
|-
|}

==PCB/Construction Photos==
<gallery perrow=3 widths=240px heights=120px>
File:rev0VTx_VCO_PCB_Bottom.jpg|Bottom of unpopulated PCB
File:rev0VTx_VCO_PCB_Top.jpg|Top of unpopulated PCB
File:rev0VTx_VCO_Top.jpg|Populated PCB
</gallery>

SA LPF - Revision history

WikiSysop: Created page with "{{navup |previous=SNA |up=Spectrum_Analyzer |next=SA_LO1}} This page describes the input/TG low-pass filter for the DIY Spectrum Analyzer. ==Summary== File:Rev0VTx_VCO_Sc..."