Copyright 2012 - 2016 Great Scott Gadgets These files are part of HackRF. This is a free hardware design; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This design is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this design; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301, USA. Opera Cake is an RF switching add-on for HackRF One. hardware notes: Schematic and layout files were designed in KiCad, an open source electronic design automation package. order of copper layers: Copper 1: C1F (front) Copper 2: C2 Copper 3: C3 Copper 4: C4B (back) PCB description: 4 layer PCB 0.0646 in Copper 1: 1 oz copper (1.4 mil) Dielectric 1-2: 6.7 mil prepreg Copper 2: 0.5 oz copper (0.7 mil) Dielectric 2-3: 47 mil core Copper 3: 0.5 oz copper (0.7 mil) Dielectric 3-4: 6.7 mil prepreg Copper 4: 1 oz copper (1.4 mil) FR408 or similar substrate with Er=3.66 (+/- 0.1) double side solder mask green double side silkscreen white 6 mil min trace width and 6 mil min isolation PCBs of this specification are available from OSH Park.