Improve ACLR Performance In Radio Channels With DPD Demodulator


Improving transmitter adjacent channel leakage ratio (ACLR) performance made easy with new digital pre-distortion (DPD) demodulator from IDT while reducing costs by eliminating the need for external IF amplifiers, baluns, switches and DSAs. ACLR is defined as the ratio of the transmitted power to the power in the adjacent radio channel. Both powers are measured after a receiver filter. As stated in the release, the DPD demodulators feature IDT’s patented zero-distortion and glitch-free technologies and are footprint compatible.

According to product description, “The IDT F1358 is a highly linear complex IF DPD demodulator with built-in digital step attenuator (DSA) and single-pole-double-throw switches (SP2Ts). It receives the signal coming out of the PA so that the I&Q data at Baseband can be pre-distorted before being sent to the Tx DAC to counteract the distortion inherent in the downstream PA. The signal coupled from the PA is adjusted via a DSA to a lower level and then sub-sampled at an IF frequency of ~200 MHz which necessitates the need for a highly linear demodulator to downmix to quadrature IF from the Transmit frequency.”



Adding further, the release mentions that any distortion in this path will degrade the performance of the DPD algorithm. By utilising an ultra-linear demodulator with integrated DSA such as the IDT F1320/F1370, the ACLR and/or power consumption of the full Tx system can be improved significantly. The operating frequency of F1358 is defined from 3200-4000MHz which enhances the performance of the digital pre-distortion transmitter linearisation path of cellular base stations.

The F1320 reduces power consumption by over 1 Watt compared to conventional solutions, and delivers high reliability with an intercept point of 4 dBm up to 105 degrees operating temperature. The following device comes in a 6 x 6mm 36-VFQFPN package.

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The key features are as highlighted below:

  • Wide flat performance IF BW
  • Wide RF and LO BWs (800MHz)
  • Ideal for Multi-Carrier Systems
  • Drives ADC directly
  • Ultra linear +42 dBm IP3O
  • Excellent ACLR performance
  • 200 Ω output impedance
  • Fully integrated DPD demodulator
  • 6x6mm 36-pin package
  • Standby Mode with Fast Recovery
  • ICC:  230mA


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