What is the Dynamic Range of a Mixer?

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Editorial Team - everything RF

Jun 18, 2019

The Dynamic Range of a mixer is the signal power range (in dB) over which the mixer will operate properly i.e it is the ratio of highest signal level a device can handle, in dB relative to 1 mW of power (dBm), to the lowest signal level it can handle (in dBm). Dynamic Range is typically expressed in dB.

The highest-level signal can be defined by 1-dB compression point. So, the dynamic range of a mixer is defined by 1-dB compression point at the higher end and the mixer noise figure at the lower end. For most passive mixers, the noise figure is very low (similar to the thermal noise) so the effective Dynamic Range of a mixer is determined by the P1dB.

In RF Mixers the P1dB (1 dB Compression Point) occurs at an amplitude of about 5 to 10 dB below the LO (Local Oscillator) power applied to the mixer. This enables us to estimate the P1dB and Dynamic Range of the mixer based on the LO Power.

Similarly, if the IP3 of a mixer is given, we know that the P1dB will be 10 -12 dB lower than this (rule of thumb) which can be used to estimate the dynamic range of a mixer.