Design of RF Remote Control Transmitter Using SAW Resonator

SAW resonator enabled RF remote control transmitters still has largest market share today, especially on 300 – 450 Mhz OOK transmitters, so research into the design of SAW resonator enabled remote control transmitter is still very important.

For every remote control transmitter application, we always recommend surface mount components and carefully designed RF PCB layout to ensure highest output power and best harmonic suppression. Best achievable performance occurs when the ground of the SAW device and two surrounding capacitors, are physically close, preferably a single point on the PCB, that’s what we should first pay attention to.

RF transistor models selection may be either BFS-17A, MMBR-901, MMBTH-10LT1, MMBTH-17LT1 or similar NPN silicon transistor such as 2SC3356. Two surrounding capacitors and one inductor are the most critical components and will require value optimization for each PCB layout or other design change.

We would recommend using two-step design process to determine onboard inductor value, first use SMD component to determine the value first, then use PCB inductor to replace SMD component, to save cost and increase performance.

For starter design in most circumstances, consider utilizing old values for start, and fine tuning if possible, and always use battery is 5V – 12V to enable RF transistor to work, use 12V if possible to have most optimized range.