sfusatclub / cubesat-radio

Cubesat comms module designed for the Canadian Satellite Design Challenge

CubeSat-Radio

KiCad project of the cubesat radio test article in preparation for the Canadian Satellite Design Challenge

This repository uses the SFU Satellite Team's KiCad component library as a submodule. To start working on the repository:

1. Open the git shell
2. Navigate to the directory you wish to place the repository inside
3. git clone --recursive "https://github.com/SFUSatClub/CubeSat-Radio.git"
4. cd .\CubeSat-Radio\KiCad-Lib\
5. git checkout master

If you modify either the component schematic or footprint libraries you must push those changes to the SFUSatClub/KiCad-Lib repository.

cubesat-radio's Issues

RF Switching

Currently a the architecture is
antenna --- diplexer --- Switch --- PA
| |
Upper band LNA

This introduced ~0.5db of attenuation at the diplexer and a further 0.5db at the switch. If we eliminate the switch and use a SP4T RF switch we can reduce the total loss to 0.5db

http://www.skyworksinc.com/uploads/documents/SKY13388_465LF_201403H.pdf

Check Connector Labeling

Check labels on jumpers, SMA connectors, PC/104 connector, test points.
I forgot to label the LEDs.

add connectors for the separation switches

1 high current connector on the +y, -x corner
1 high current connector on the -y, +x corner

Check RF path

Check CPWG, passives, wall of ground vias.

Wire crimps for power connector

Add them to the BOM

Add band select filter

Add a wide band 1 pole band selec filter infront of the LNA

Make component reference easier to see

Orient reference designation in one direction such that footprints are easy to find during assembly.

RF6886 Vreg Range Unknown

In Amp_dev we assumed Vreg had a maximum value of 3.1V but LOG10(ref-sense) vs Pout graph states full scale 3.2V for Vreg. Add a pot so that we can control the positive rail fed to the opamps

Flip the signals on the debugger connector (P1)

Add BOM information in KiCad

Add digikey and mouser numbers to all components

Add controlled impedance strip

For making microstrip impedance and loss measurements

Add label silkscreen for writing on

Investigate issues with LEDs

Impedance Controlled Trace Clearance

Current microstrip geometry: 0.2mm space, 0.336mm width

The space to ground should be 0.3mm according to the calculation. However, a 0.3mm clearance cannot be assigned to either the RF net class or the ground pour due to small SMD pitch.

We can either:

1. Create a large no fill zone around the RF net class and use the microstrip instead of a coplanar wave guide.
2. Maintain 0.2mm clearance and modify trace width to 0.315313mm
   

Look into U.FL connectors for RF test

Assuming that we run out of space, we may need to go to a connector smaller than SMA for the test connectors

Formalise Antenna Connection

Confirm with Structural regarding placement of SMA connector

Finish power planes

Comply with PCBway min mask width

minimum solder mask width: 150um
Check all components.
Change mask setting on board or in footprint library?

Add temperature sensor

Add I2C SMT temp. sensor. Add information onto the systems spreadsheet.

For Rev_3 use commit for release

Rather than making a branch for every revision, let's use GitHub's release feature and reference a commit

Add keepout under wirewound inductors

Check Ground plane

Pay attention to copper islands.
Pay attention to return current paths especially for VCC_* and microstrip.

Power Supply Architecture

The comms module requires a high current 3.6V rail and low current 3.3V, 3.1V rails. All of these rails requires good noise isolation from the rest of the spacecraft (specifically the switching regulators that generates the parent rails). The system architecture must be agreed upon for the entire spacecraft before we can proceed.

Need ability to probe desired points in RF path

Add a vertical SMA population option between CC1125 and balun, balun and switch, and switch and front end

Reduce text thickness

Reduce the text thickness on the silkscreen, not the component reference but the other miscellaneous labels. Currently the thickness makes the text blotchy.

Fix the PA BOM matches the RFMD evaluation board, NOT the RF6886 datasheet

Noticed some discrepancies between the RF6886 datasheet components and those specified in the BOM we received from Qorvo for the RF6886 evaluation board. Update the PA schematics (both bands) so that the parts match the RF6886 evaluation board BOM

Check PC104 layout

Check board size, mechanical hole size, plating, position, connector position.

Add RF shielding to PA

We currently have stock of these https://www.digikey.ca/product-detail/en/laird-technologies-emi/BMI-S-101/903-1006-1-ND/2175956 that was never used.

Move POT for VPC control to ground, fixed resistor to 3v3

Fixed resistor should be 3.2K, POT will be the same one used for Rev_1.
This way turning the POT full way will result in 2.5V or 0V.
Considered 50K pull down present in SKY65366-21 for calculation.

Make the board one sided

That way we can reflow all SMD components

Replace CC1125 with CC1101

Fix switch for PA/LNA bypass

Invert the LB switch controls to ease routing

Currently, the LB switch orientation and the RF output switch orientation forces the RF paths to cross:

Add an inverter to the LB switch control signal so that we don't need to cross the signals

Flip PC104 connector pins

Although the library component for the PC104 connector was updated, the change did not propagate to the RF board:

Row B should be on the left row B on the right.

Add reverse polarity protection

P-Fet on high side input

2N7002DW pin assignment incorrect

Component pin assignment is incorrect. Please read datasheet https://www.diodes.com/assets/Datasheets/ds30120.pdf

TX and 3V6 indicator LEDs do not work because of this.

IC pad separation must be 30 mil

IC pads and passive component pads must be separated by a minimum of 30 mils. This is to prevent solder from spilling off the IC pad and pulling the passive component in.

RBF Switch

Not enough space on the computing board for the roller switch. Will need to go on the RF board due to access panel requirements.

Double check connectors

Place silkscreen

Incorporate connector ESD connection

Check debug connector pinout against CC debugger

Debug connector is P1

Check potentiometer connections

The past few revs has had improperly connected potentiates. Please check.

Find a better potentiometer

Our current SMD pot breaks too easily.
Find a rugged through hole one

Add club logo on silkscreen

Reset push button and LED

push button and indicator LED on RESETn pin

Add DC Barrel Jack for Vin

Component: 3pin-DC-power
Footprint: SFUSat:PJ-028-SMT-TR-3pin-DC-jack
Center pin positive: +V on pin 1

Adjust solder paste aperture sizes

• Make passive apertures larger
• Make IC thermal aperture smaller

Clear space for Antenna Feed Cable assembly

Space between the RF board and the antenna feed board is tight. The height of the SMA jack and SMA right angle connectors together are going to be tall and therefore need special accommodation on the board.

Draw the locations of interest on the fab layer.

Integrating capacitor on the second op-amp of PA feedback

Use 0603 cap, minimum value 0.2uF.

Minimum capacitance value was determined with power setting (pot) set to 0 and input at 10dbm.