---
# System prepended metadata

title: 'Issue: \<Solved\> High Rfb of IV Converter'
tags: [HW-Circiut, DeWei, issue]

---

# Issue: \<Solved\> High Rfb of IV Converter


## Background

![](https://i.imgur.com/gMaSUHr.png)

* If the light source is not very bright, *R1* should be rised
* For our previous result of experiment(1 OPA IVCvT)
  * R1 = 500k
  * Vo = 3.3V 
  * ~200 Lux (Estimated by [BPW21R Datasheet](https://www.vishay.com/docs/81519/bpw21r.pdf))
  * ![](https://i.imgur.com/ZvLe7e0.png)

## Problem

* [Resistor has max value on PCB](https://electronics.stackexchange.com/questions/180580/what-is-the-resistance-of-a-typical-pcb)
  * > If you're using a 10M resistor and want to maintain 0.1% tolerance (e.g. for a DMM input divider) that means that the board resistance certainly can't be less than 10G ohms. 
  * > If you really need high impedance for fA measurements, PTFE standoffs or air connections are better than FR4. 

* [4kT Noise](https://electronics.stackexchange.com/questions/563136/trouble-to-understand-johnson-nyquist-noise-why-i-dont-find-the-4-in-the-vol)
## Possiable solution

* [Replace PN-PD with PIN-PD](https://www.teamwavelength.com/download/applicationtechnotes/an-ld17.pdf)
  * ![](https://i.imgur.com/E7zDFnB.png)
* [Intrusment AMP to implement High Gain (3 OPAs)](https://doi.org/10.1364/OE.27.002125)
  * Problem: OPA matched
* [T-Tree](https://electronics.stackexchange.com/questions/333055/op-amp-with-t-network-in-the-feedback-path)
###### tags: `issue` `DeWei` `HW-Circiut`