

# Analog Spiking Neuron Circuit - Caravel Submission

This is the Google/EFabless/Skywater Caravel submission of an [Analog Spiking Neuron Circuit.](https://ieeexplore.ieee.org/document/9184447) The submission also includes a SONOS transistor array. 

## Neuron circuit
The circuit in the original paper is in 130nm technology and has a vdd of 300mV. Skywater pdk is hybrid 180nm/130nm node where the minimum transistor length is 150nm.
As a result vdd needs to be higher in order to get the circuit to work properly. In simulation 700mV seems to work well. 

<p align=”center”>
<img src="/doc/neuron.png" width="75%"> 
</p>

### pinout
| node   | pad         | node      | pad         |
|--------|-------------|-----------|-------------|
| i_bias | mprj_io[13]  | v_buff    | mprj_io[22] |
| vad    | mprj_io[14]  | u_buff    | mprj_io[23] |
| vr     | mprj_io[15]  | a_buff    | mprj_io[24] |
| vk     | mprj_io[16] | axon_buff | mprj_io[25] |
| vth    | mprj_io[17] | sel       | mprj_io[26] |
| vw     | mprj_io[18] | v_syn     | mprj_io[27] |
| vau    | mprj_io[19] | u_syn     | mprj_io[28] |
| vsyn0  | mprj_io[20] | a_syn     | mprj_io[29] |
| vsyn1  | mprj_io[21] | axon_syn  | mprj_io[30] |
|        |             | i_in      | mprj_io[31] |

### extracted netlist simulation 
Spiking pattern at v_buff for i_in = 10pA DC 
<p align=”center”>
<img src="/doc/sample_sim.png" width="75%"> 
</p>

## SONOS array
A 2x2 array of nfet sonos cells with transistor sizing 420nmx150nm.
<p align=”center”>
<img src="/doc/sonos.png" width="75%"> 
</p>

### pinout
| node | pad         |
|------|-------------|
| WL0  | mprj_io[7]  |
| WL1  | mprj_io[8]  |
| BL0  | mprj_io[9]  |
| SL0  | mprj_io[10] |
| BL1  | mprj_io[11] |
| SL1  | mprj_io[12] |


# Installation
To setup and install the repo for development:

1. Install prerequisite tools:
   1. Install [Magic VLSI Layout Tool](http://opencircuitdesign.com/magic/)
      - Note: As of 12/7/2020 you must install Magic from source code. The packaged version will not work with OpenPDKS.
   2. Install [KLayout](https://www.klayout.de/build.html)
   3. Install [SkywaterPDK](https://github.com/google/skywater-pdk) and [OpenPDK](https://github.com/RTimothyEdwards/open_pdks) using [OpenLane](https://github.com/efabless/openlane.git)
      1. Clone and Install OpenLane. This will also grab and install SkywaterPDK and OpenPDK for you.

```shell
export PDK_ROOT=(where pdks will be installed)

cd $PDK_ROOT

git clone https://github.com/efabless/openlane.git -b mpw-one-a

cd openlane
export OPENLANE_ROOT=$(pwd)
make
```

​			2. Clone and uncompress the repo

```shell
git clone https://github.com/Bryce-Readyhough/caravel_UNCC_MPW_1.git
make uncompress -j$nproc
```