The IDT F1978 Digital Step Attenuator (DSA) featuring Glitch-Free™ technology improves system reliability and settling time.  It has an attenuation range of 31.5dB with excellent accuracy and very low distortion and insertion loss. The product supports new Direct serial mode programming as well as Conventional serial programming and Parallel programming modes of Direct and Latched.
The F1978 DSA has identical RF performance as the F1975 DSA. The difference between F1978 and F1975 is that F1978 has an additional programming mode called Direct Serial Programming. Consult the "Programming" section of the F1978 datasheet or application note AN-945 “Comparison of F1975 and F1978 Digital Step Attenuator Serial Programming Methods”.


  • 5MHz to 3000MHz frequency range
  • Glitch-Free™ low transient overshoot
  • Low insertion loss 1.2dB at 1GHz
  • Excellent linearity +64dBm IIP3
  • Attenuation step error 0.1dB at 1GHz
  • Serial and parallel interface 31.5dB range
  • Low spurious design
  • 3V / 5V supply, 1.8V / 3.3V control logic
  • Fast settling time
  • Class 2 JEDEC ESD (2kV HBM)
  • 4 x 4 mm 20-TQFN package

Product Options

Orderable Part ID Part Status Pkg. Code Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
F1978NCGK Active NCG20P1 VFQFPN 20 K Yes Tray
F1978NCGK8 Active NCG20P1 VFQFPN 20 K Yes Reel

Technical Documentation

Title Other Languages Type Format File Size Date
Datasheets & Errata
F1978 Datasheet Revision O Datasheet PDF 3.68 MB
Application Notes & White Papers
AN-945 F1975-1978 Serial Programming Methods Application Note PDF 193 KB
AN-896 RF Products EVS Digital Control Software Guide Application Note PDF 2.91 MB
Digital Step Attenuators Product Overview 日本語, 简体中文 Overview PDF 185 KB
IDT Products for Radio Applications 日本語 Product Brief PDF 2.34 MB

Software & Tools

Title Other Languages Type Format File Size Date
F1978 S-parameters Model - S-Parameter ZIP 869 KB
RF Digital Control Software Installer Software Tool ZIP 169.81 MB

Evaluation Boards

Part Number Title Sort ascending
F1978EVBI Evaluation Board for F1978, 6-bit, 75 Ohm, Digital Step Attenuator