Difference between scalar mixer and vector mixer in RF design
This page compares scalar mixer vs vector mixer and mentions difference between scalar mixer and vector mixer used in rf and microwave circuit designs.
RF mixer is a three-port device. The three ports are usually denoted as radio frequency (RF), intermediate frequency (IF), and local oscillator (LO). The RF and IF ports are bidirectional ports. Since a mixer has three ports, this means that it has nine S-parameters.
RF mixers are categorized into following types.
• 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
• This mixer helps in measurement of RF parameters which are related to magnitude part only.
Hence it is known as scalar mixer.
• SNA equipment is used for scalar measurements related to scalar mixers.
• Scalar mixer common parameters : Magnitude Conversion Loss, Isolation, Reflection, 1 dB Compression Point, Intermodulation, Noise Figure etc.
• This mixer helps in measurement of RF parameters which are related to magnitude and phase both.
Hence it is known as vector mixer.
• VNA equipment is used for vector measurements related to vector mixers.
• Vector mixer common parameters : Absolute and Relative Phase, Absolute and Relative Group Delay, Group Delay Ripple, Deviation from Linear Phase, Magnitude Ripple etc.
Challenges of Vector Mixers
Limitations or challenges of Vector Mixers are as follows.
• RF and IF frequencies are different
• All VNA receivers (reference & measurement) work on identical frequencies
• LO phase has a direct impact on IF phase
• Full system error correction requires a frequency converting Through standard
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