analog-amsat: 1.3-3.6 GHz Fractional-N Phase Locked Loop and Bandgap reference aimed at Amatuer Radio Satellite Transceiver.

Clone this repo:
  1. e82faa7 final gds & drc results by Jeff DiCorpo · 4 months ago main mpw-one-final
  2. 9e2226c final gds & drc results by Jeff DiCorpo · 5 months ago
  3. 53bef45 Removed extra dnwell shapes by yrrapt · 5 months ago
  4. 6b4a592 Update to use openlane version of digital by yrrapt · 5 months ago
  5. 10a18df Version with flattened user_project_wrapper passed through magic by yrrapt · 5 months ago

Amateur Radio Satellite Transceiver (SKY130) - Caravel Submission

This is the Google/EFabless/Skywater Caravel submission of the Amateur Radio Satellite Transceiver.

Design

These blocks serve as the first pieces in a larger design of an open source amateur radio satellite transceiver - this is the first tapeout submission.

The design sources of the continued project can be found here: amsat_txrx_ic.

1.3 - 3.6 GHz Fractional-N Phase Locked Loop

pll VCO Layout

A S-Band phase locked loop employing a differential ring oscillator VCO with quadrature outputs. CML (Current Mode Logic) and flip-flop based pre-scaler dividers are used with a fractional-N divider which uses a 3rd order MASH structure with dithering. Finally a PFD (Phase Frequency Detector) is combined with a charge pump with off chip filtering to complete the loop.

A cell based buffer is used to drive the external 100 ohm differential output.

Bandgap

bandgap Bandgap Layout

A bandgap reference with separate PTAT and CTAT currents. Provides less than +/-0.2% variation from -40 to 125 degrees celcius (tt simulation). 6 bits of trimming on both PTAT and CTAT allows less than 1% accuracy over process variations.

Using the sources

To install the environment used for development of this repository, follow these instructions.

  1. Install the tools:
git clone https://github.com/yrrapt/sky130_setup.git
cd sky130_setup
./install_pdk.sh
./install_tools.sh
  1. View schematics:
cd amsat_txrx_ic-caravel/xschem
xschem
  1. View layout:
cd amsat_txrx_ic-caravel/gds
klayout caravel.gds
  1. Run DRC:
cd amsat_txrx_ic-caravel/utils
./run_drc amsat_txrx_ic-caravel
  1. Run LVS:
cd amsat_txrx_ic-caravel/utils
./run_drc amsat_txrx_ic-caravel