ADC Board
From SpaceWeather
Contents |
Board Blocks
Antenna Input
The biconical antenna is connected to the board via a BNC connector. The termination on the antenna end is matched to 50 Ohms, so we may not need to include termination resistors. We may also not connect the ground terminal of the BNC to the ground plane if we want to keep the reference voltage separate from the board ground.
Over Voltage Protection
The next block is over-voltage protection in the form of a high-current Zener diode from Littelfuse. This will protect the downstream components and limit the positive and negative voltage swings coming from the antenna.
Low Pass/Amplifier
The antenna is not sensitive below 30MHz, so any energy in that spectrum is noise and will be zeroed out in this stage. Since we are using an Active Low-pass Filter, we could also amplify the signal by adjusting the gain in this stage.
- <math>
f_{\text{c}} = \frac{1}{2 \pi R_2 C} </math>
ADC
Power and Routing
In our high performance application, we will be using small surface mount packages to save space and minimize parisitic inductances.
Here is a link to popular surface mount packages for capacitors and resistors: media:SMT Packages.PNG
Bill of Materials
| Reference Name | Manufacturer | Manu Part # | Digi Key # | Quantity | Note |
|---|---|---|---|---|---|
| U4 | TI | ads5463 | 296-21323-ND | 1 | 12-bit 500 MSPS Analog Digital Converter |
| U1 | Nat Semi | LMH6628 | LMH6628MA-ND | 1 | Dual Wideband, Low Noise, Voltage Feedback Op Amp |
