Amateur Radio Satellite Transceiver (SKY130) - Caravel Submission

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


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 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 cd sky130_setup ./ ./

  1. View schematics: cd amsat_txrx_ic-caravel/xschem xschem

  2. View layout: cd amsat_txrx_ic-caravel/gds klayout caravel.gds

  3. Run DRC: cd amsat_txrx_ic-caravel/utils ./run_drc amsat_txrx_ic-caravel

  4. Run LVS: cd amsat_txrx_ic-caravel/utils ./run_drc amsat_txrx_ic-caravel

Layout Image
Thomas Parry
Organization URL
Amatuer Radio Satellite Transceiver (Sky130) - Caravel Submission
['open Mpw', 'bandgap', 'vco', 'pll', 'mpw-One']