Ramy Rady

Research

My Ph.D. work at Texas A&M combined CMOS circuits and silicon photonics to build wideband, reconfigurable mm-wave radios. The sections below cover each thread, its published results, and the papers behind them.

Talks

My Ph.D. research in three minutes Three-Minute Thesis (3MT®) finalist, IEEE Microwave Week 2023 Video: IEEE Microwave Theory and Technology Society · Watch on YouTube

Wideband mm-wave CMOS / silicon photonic receivers

Radios for 5G and beyond must pick a narrow channel out of tens of gigahertz of spectrum while strong interferers sit nearby. Filtering at mm-wave frequencies is lossy and hard to tune in CMOS alone. I moved the filtering into the optical domain: the RF signal is modulated onto light, shaped by reconfigurable silicon photonic filters, and converted back by CMOS electronics.

Key results

  • 25–40 GHz tunable receiver front-end selecting four 5 GHz-wide channels (IMS 2021)
  • Front-end extended to 20–43.5 GHz for channel selection and jammer rejection (JLT 2023)
  • Hybrid-integrated CMOS/Si-photonics software-defined radio receiver with >80 dB rejection of <−10 dBm in-band blockers (RFIC 2023)
  • Reconfigurable heterodyning receiver architecture (TMTT 2024)
Papers (4)
CMOS Si photonics CMOS LNA MZM laser tunable pole/zero filter rejects blockers PD TIA RF → light → filtered in optics → back to RF
Concept: the RF signal is moved onto light, filtered by tunable silicon photonic rings, and converted back by CMOS.

Automatic tuning of silicon photonic filters

Silicon ring resonators shift with fabrication variation, temperature, and thermal crosstalk, so a filter that works on paper rarely works out of the box. I built closed-loop calibration: on-chip monitors, a TIA/ADC/DAC/microcontroller loop, and ML-based algorithms that set heater biases and place the filter's poles and zeros automatically.

Key results

  • External-modulator-based tuning of 4th-order all-pass-filter pole/zero filters (OFC 2021)
  • Automated tuning for silicon photonic filters (OFC 2022)
  • Automatic tuning of microwave silicon photonic ring resonators (SiRF 2023)
  • mm-wave silicon photonic circuits with automatic calibration (WAMICON 2023)
Papers (5)
heater ring tap PD TIA ADC ML controlμC DAC closed loop sets each pole/zero automatically
Concept: on-chip monitors and a controller set each ring's heater until the filter matches its target response.

Radio-over-fiber links and microwave photonic drivers

Distributed antenna systems carry mm-wave signals over fiber to remote antenna units. That needs wideband, linear electro-optic conversion at the antenna and efficient CMOS drivers for the modulators. This work spans the remote antenna unit itself and the Mach–Zehnder modulator drivers that feed it.

Key results

  • Automatically tunable mm-wave remote antenna unit (MWP 2022)
  • Ultra-wideband remote antenna unit for radio-over-fiber distributed antenna systems (Optics Express 2024)
  • Power-efficient 20–35 GHz MZM driver with programmable linearizer in 28 nm CMOS (OFC 2021, TMTT 2023)
  • 16–32 GHz RF photonic front-end with 22 nm CMOS driver and travelling-wave MZM (IPC 2023, JLT 2024)
  • Invited review of microwave silicon photonic drivers and MZMs (IEEE Microwave Magazine 2026)
Papers (7)
Central office Antenna unit RF driver MZM laser fiber PD PA mm-wave carried over fiber to the antenna
Concept: a radio-over-fiber link, from the CMOS modulator driver to the silicon photonic remote antenna unit.

Energy-efficient CMOS transceivers

Earlier work focused on how little power a link can use. That includes a short-range transmitter supplied directly from an integrated switched-capacitor DC–DC converter (my M.Sc. thesis), and inverter-based optical receivers for wireline links.

Key results

  • Ultra-low-power 65 nm CMOS radio TX link powered by a switched-capacitor DC–DC converter, achieving 2 Mbps (TCAS-II 2020)
  • 12.5 Gb/s, 1.38 mW inverter-based optical receiver in 28 nm CMOS (MWSCAS 2022, AICSP 2024)
Papers (3)
TX link SC DC–DC VCO PA 2 Mbps Optical RX PD inverter TIA CTLE 12.5 Gb/s 1.38 mW
Concept: an ultra-low-power transmitter supplied by an integrated DC–DC converter, and an inverter-based optical receiver.

Industry work

Industry projects are proprietary, so only a summary appears here. See the CV for more.