Behavioral Model for Characterizing & Pre-compensating Non-Linear Systems


Description of Technology

Researchers at the University of Calgary have developed a new behavioural model for accurately characterizing non-linear systems which include strong memory effects. This model accurately characterizes RF transmitters which allows digital pre-distortion (DPD) techniques to more effectively compensate for transmitter non-linearities. Conventional models do not account for the strong memory effects exhibited by wideband power amplifiers (PAs). The new model has very low complexity, making it suitable for FPGA or ASIC implementation in cost-and-power sensitive devices such as mobile handsets.

This behavioural model has been implemented in the Amplifier and Predistorter Simulation (AMPS) program, a software package designed to simplify the simulation and evaluation of amplifier and predistorter models. Fore more information and to download a free trial version of AMPS, visit

Areas of Application
  • Base station and handset transmitters for 3G, 4G and 5G cellular networks
  • Control systems
IP Status
Competitive Advantages
  • Significantly reduced out-of-band emissions compared to those produced by memoryless pre-distorters
  • 3G, 4G, and 5G networks require fewer base stations due to increased cell size
  • System capacity benefits from improved transmit EVM and reduced out-of-band emissions
  • Very low implementation complexity, suitable for low-cost and power-sensitive devices
  • Applicable to most non-linear systems exhibiting strong memory effects
  • Compatible with multi-band systems
  • Enables fast prototyping
Stage Of Development

Experiments conducted using a two-carrier WCDMA signal sent through a transmitter suitable for 3G wireless base stations have demonstrated that the new pre-distorter suppresses out-of-band emissions by more than 20 dBc relative to the transmitter’s spectrum with no pre-distortion. An improvement of approximately 10 dBc is observed when comparing the new pre-distorter to a conventional Wiener pre-distorter. The researchers have also developed a software tool (UTI Ref. #720.2) which developers can use to characterize a real transmitter and to design a suitable pre-distorter for it.