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Line Injector

This repository contains the schematics and mechanical files for a line injector.

Contents

Introduction

A line injector can be used to inject a ripple voltage into the supply line of a circuit. This can, for example, be used to measure the power supply rejection ratio (PSRR) of a regulator.

Key Features:

  • Bandwidth (-3 dB): 6 Hz - 35 MHz (into 50 Ω)
  • Passband transfer function is about 0.95 V/V (@ 5V) and 0.975 V/V (@ 15V)
  • Maximum input voltage: 50 V
  • Maximum current: 5 A
  • Remote sensing inputs to compensate for the voltage drop over the MOSFET

Line injector pcb

The design was done using KiCAD 8.

Bode Plot

Bode Plot

Additionally, a report from the Bode 100 VNA used to characterize the injector can be found here.

Photos of the finished design

Front

Line injector photo front

Back

Line injector photo back

PCB

Line injector photo back

PCB Design Files

The root folder contains the KiCAD files. The bill of materials can be found on the releases page along with Gerber files for production.

Mechanical Design Files

The PCB fits into a Hammond Manufacturing 1457N1201EBK case. Additionally a few drilled holes need to be drilled for the connectors.

Related Repositories

See the following repositories for more information.

KiCAD footprints: https://github.com/PatrickBaus/footprints.pretty

Versioning

I use SemVer for versioning. For the versions available, see the tags available for this repository.

  • MAJOR versions in this context mean a breaking change to the external interface of the hardware like different connectors or functions.
  • MINOR versions contain changes to the hardware that only affect the inner workings of the circuit, but otherwise the performance is unaffected.
  • PATCH versions do not affect the schematics or invalidate older bill of materials. These changes may include updated components (to replace obsolete parts for example), an updated silkscreen, or fixed typos.

License

This work is released under the CERN-OHL-W See https://ohwr.org/cern_ohl_w_v2.pdf or the included LICENSE file for more information.