Extensive experience with system designs involving RF transmitters and receivers ranging from 10 MHz up to 2.5 GHz for a wide variety of applications. Ultra-miniature custom radios that use the latest developments in miniature electronics technology from dozens of manufacturers, with component case sizes down to 0402 and 0201 and innovative PCB layout techniques for shielding and isolation. Products include system design–both hardware and software–of sensitive superhet and direct conversion receivers, low and high power transmitters, and custom antennas. Products have used a variety of analog and digital modulation schemes (PPK, FM, FSK, GMSK, DPSK, OFDM, DSSS, on/off keying, and more). Hardware designs including component selection, schematic development, and PCB layout of antennas, RF and IF amplifiers, mixers, PLL/VCO loops, baluns, diplexers, splitters, attenuators, filters (ceramic/SAW/discrete), RF switches, log detectors, IQ demodulators and modulators, and more. Systems have also included design of digital sections,including ADCs and DACs, selection and software design of microcontrollers and FPGAs. Also experience selecting and using off-the-shelf radio modules for GPS, WiFi, analog and digital video transmitters and receivers data modems/transceivers, and more. Many designs are in mass production (5,000+ units shipped) and still in wide use today (see page bottom for more detail on products and applications).
- Summary
- Dozens of designs that include RF transmitters and receivers, using both custom and off-the-shelf modules, often mixed
- PCB designs that include ultra-miniature radios that require careful isolation, microstrip and striplines, and stub matching networks
- Many modulation techniques, including FM and FSK, PPK (on/off keying), DPSK, frequency hopping, and more
- Component selection including low-power amplifiers, high-power amplifiers, baluns, mixers, log detectors, IQ modulators, IQ demodulators, RF switches, band-, low-, and high-pass filters, power splitters, power attenuators, duplexers and diplexers, RF board-to-board connectors, RF board-to-cable connectors, antenna selection, custom antenna design, and more
- Superhet receiver design including selection of IF frequency and system bandwidth and trade-offs with system noise figure (NF) and signal-to-noise ratio (SNR), and the effects of each on overall system performance (sensitivity, out-of-band rejection, and noise immunity)
- Firmware designs that implement parity checking, forward error correction and detection, dynamic trigger levels, multi-symbol detection schemes in the IQ plane, digital filters, RF power meters, Reed-Solomon and other cyclic error-correcting codes
- Designs that include WiFi, data modems (900 MHz, 1.3 GHz, and 2.4 GHz), GPS, custom superhets, high-power pulsed transmitters, video transmitters and receivers
- Experience with custom antenna designs and off-the-shelf antenna selection for various applications (PCB-mount, rooftop, wire whip, bulkhead, and custom-geometry) both internal and external to product enclosure. Experience includes extensive time in anechoic chambers characterizing antenna radiation patterns and efficiency, and converting results to expected system performance (typically range and link margin). Understanding of trade-offs between antenna aperture size, bandwidth, and efficiency.
- Microcontrollers for PLL register programming and monitoring, channel selection, and more. Requires innovative shielding and isolation techniques for co-location of noisy digital components and sensitive RF on the same board
- FPGA/CPLD for interface with high-speed ADCs and DACs, I/Q demodulators, log detectors, RF switches, enable switches, and more requiring careful PCB layout to ensure full decoupling between RF and digital board sections
- Power supply designs for high-power RF amps requiring custom, sometimes high DC voltages and designs for ultra-sensitive receivers (e.g. superhet, direct conversion, GPS LNA) requiring low noise power supply design and careful decoupling
