Terminology » RF Components » Scalar vs. Vector Mixers in RF Design: Key Differences

Scalar vs. Vector Mixers in RF Design: Key Differences

rf mixer scalar mixer vector mixer network analyzer rf design

This article compares scalar mixers and vector mixers, highlighting the differences in their applications within RF and microwave circuit design. An RF mixer is a three-port device typically labeled as radio frequency (RF), intermediate frequency (IF), and local oscillator (LO). The RF and IF ports are bidirectional. With three ports, a mixer is described by nine S-parameters.

RF mixers are categorized in several ways:

  • Scalar mixer and Vector mixer
  • Single balanced mixer, Double balanced mixer, Triple balanced mixer
  • Image reject mixer and Non-image reject mixer
  • Diode mixer, Harmonic mixer

rf mixer

Scalar Mixer

  • This type of mixer is used to measure RF parameters related to magnitude only. This is why it’s called a scalar mixer.
  • Scalar Network Analyzers (SNAs) are used for scalar measurements with these mixers.
  • Common parameters measured with scalar mixers include: Magnitude Conversion Loss, Isolation, Reflection, 1 dB Compression Point, Intermodulation, Noise Figure etc.

Vector Mixer

  • This mixer is used to measure RF parameters related to both magnitude and phase. Hence the name, vector mixer.
  • Vector Network Analyzers (VNAs) are used for vector measurements with these mixers.
  • Common parameters measured with vector mixers include: Absolute and Relative Phase, Absolute and Relative Group Delay, Group Delay Ripple, Deviation from Linear Phase, Magnitude Ripple etc.

Challenges of Vector Mixers

Vector mixers present some challenges:

  • RF and IF frequencies are typically different.
  • All VNA receivers (reference & measurement) operate on identical frequencies.
  • The LO phase directly affects the IF phase.
  • Full system error correction requires a frequency conversion.