Columbia University

Technology Ventures

RF receiver with tunable self-interference cancellation for high-quality FDD and SC-FD applications

Technology #cu15077

The technology is a tunable radio frequency (RF) receiver for frequency-division duplexing (FDD) and same-channel full duplex (SC-FD) applications that employs self-interference cancellation (SIC) to support wide-band modulated signals. Using a bank of tunable second-order high-Q bandpass filters and linear N-path Gm-C filter, it can eliminate self-interference that adversely affects FDD or SC-FD at a significantly higher bandwidth than other SIC designs. It also enables SIC to be performed using a single integrated signal processor, rather than multiple duplexers or bulky off-chip circuits.

Use of a bank of tunable bandpass filters and a linear N-path filter implementation with embedded variable attenuation and phase shifting significantly improves FDD and SC-FD quality by increasing self-interference cancellation bandwidth without resorting to bulky circuitry

Frequency-division duplexing is a radio transmission technique whereby the transmitter and receiver employ different carrier frequencies so as to enable concurrent transmission and reception. Single channel full-duplex is a related capability that employs a single frequency band for both transmission and reception to make more efficient use of the frequency spectrum. Self-interference cancellation uses information from the transmitted signal to eliminate signal degradation due to interference between the transmitted and received signals. In contrast to current SIC techniques that can only perform cancellation at narrow bandwidths, require multiple off-chip duplexers, and/or rely upon bulky circuits that cannot be included in an IC, this technology enables SIC using a single compact integrated circuit while affording a cancellation bandwidth almost 10 times as wide as current techniques.

A prototype of the technology fabricated with 65nm CMOS has exhibited SIC bandwidths of up to 75 MHz for FDD and up to 25 MHz for SC-FD.

Lead Inventor:

Harish Krishnaswamy, Ph.D.


  • Wireless integrated circuits (e.g., SoCs) with multiple transceivers
  • Small form-factor FDD and SC-FD transceiver systems
  • Candidate technology for 5G mobile communication standard


  • Supports tunable bandwidth almost 10 times as wide as current FDD transceiver designs
  • Reduces need for multiple duplexers in multiband FDD transceivers
  • Improved signal quality in both FDD and SC-FD applications

Patent Information:

Patent Pending

Tech Ventures Reference: IR CU15077

Related Publications: