---
# System prepended metadata

title: Regular Meeting (2022.12.19)
tags: [Regular Meeting, DeWei]

---

# Regular Meeting (2022.12.19)

* Simulation of fanout
	* Basically, the circuit is the same to previous project
		* https://hackmd.io/M-v_rjZKSKGRH43tHGPLxA
		* Just change OPAs and Power
  * [Code](https://github.com/curly-wei/sim-fanout64.git)
  * Problem: Some *Analog Devive*\'s can't be simation
      * This project and Dr.Ken's project both has that error
          * AD8655 : This project (o)
          * AD8397 : This project (x)
          * ADA4817 : Dr.Huang project (x)
      * ***TI*\'s OPAs has not this problem**
* 2 stage of LDO is not good choice
  * [Refer to here](https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1179125/tps7a20-minimum-launch-voltage-of-tps7a20-5v/4445123#4445123)
* USB RC-Filter
  * https://andybrown.me.uk/2015/07/24/usb-filtering/
## Simulation of fanout

![](https://i.imgur.com/0iOeNR3.png)
* AD8655
* 2-stage OPAs
  * 1 channels output
  * 4.5Vcc for OPAs
    * USB 5V (type-C) and PSU 5V (2 pins Euro terminal block)
  * 1st: buffer (Emitter follower)
  * 2nd: 2 V/V Gain
  * with 50 ohm input and output
  * Input pulse
    * 20ns R/F time
    * 1us width
    * 100mV Amplitude
  * Next week I'll do 8 or 48 channels output

### Tools: ngspice + python3 + make

* ngspice
	* Crossplatform circuit simulation based on *spice* language 
	* Invoking OPAs modules(lib) which provided by vendor 
	* Describing my circuit with OPAs modules
	* Describing testbench for my circuit
	* Do simulation
	* Export *.csv*-liked plotting data
		* I called raw-data
* Python 3
	* Plotting with *.csv*-liked raw-data from *ngspice* outputted 
* make
	* Invoke and interaction between *ngspice* and *python-3*
	* Top file
		* Just run `make adxx`, will invoke *ngspice* and *python-3* for simultion adxx

### Problem

* When I run :
	* ![](https://i.imgur.com/7fyen1c.png)
* This problem exist when I run Dr.Huang's project
* Raw-data(ngspice generated) is already incorrect data, which is the same to plotted data
* But some (Analog Decice 's)OPAs has no problem: 
	* AD8655(This project)


### Possible solution

* Compatibility mode for Pspice(TI) and LTSpice(Analog device and Linear Tech) of ngspice
  * ngspice officially provided
  * TI (o)
  * Analog Device(x)

###### tags: `Regular Meeting` `DeWei`