RF Mixer Transfer Function With Respect to Phase

[strahd_von_zarovich]

Hi, i want to find my mixer transfer function with respect to phase. My mixer is Marki-ML1-0220.

Ports are 50 Ohm
LO and RF signals at 10GHz
My LO power is = 13 dBm => 1V
My RF power is = 5 dBm => 0.4V
Conversion Loss = 7dB
1dB compression(dBm) = +3dBm (neglect it)

and i filter other frequency components except DC. So how can i find my mixer transfer function respect to phase.

Lets say
RF Signal = 0.4V * cos(2*pi*f*t)
LO Signal = 1V * cos(2*pi*f*t + phi) => So DC component is (0.4*1)/2 * cos(phi) but first thing i don't know is how to add conversion loss effect to the equation. And second if we assume conversion loss is 0dB, what is the transfer function(or gain constant) . Is it directly 0.2 or 0.2*(cos(1)-cos(0)) ?
:thinker:

 

[biff44]

Phase huh? Well you are sampling the RF signal at the LO rate, so the phase information is based on when the LO sine wave hits its peak...that is approximately when the sample happens. But since the output IF frequency is not zero...what exactly does "phase" mean to you? You can put in a constant RF, and constant LO, and you will get out a varying sine wave low frequency output.

You CAN have an unknown RF signal received in one channel, and a known RF sample signal sampled simultaneously in a 2nd channel (sharing the same coherent LO), and infer some things about the unknown RF signal's "phase"

 

[strahd_von_zarovich]

Phase huh? Well you are sampling the RF signal at the LO rate, so the phase information is based on when the LO sine wave hits its peak...that is approximately when the sample happens. But since the output IF frequency is not zero...what exactly does "phase" mean to you? You can put in a constant RF, and constant LO, and you will get out a varying sine wave low frequency output.

You CAN have an unknown RF signal received in one channel, and a known RF sample signal sampled simultaneously in a 2nd channel (sharing the same coherent LO), and infer some things about the unknown RF signal's "phase"

Thanks for repply,
I put constant RF and constant LO and i want to find voltage at the mixer output.
For example if two signals have 1 degree phase difference and output voltage is V1, and at 2 degree phase difference and output voltage is V2.
My gain constant is (V2-V1) V/degree. I want to find that.

 

[ferdem]

He is asking how to use a mixer to find the phase difference between two sinusoidal signals.
Ideally, as you said, if you multiply two sinusoids, resulting DC component is directly proportional to 0.5*amplitude1*amplitude2*cos(delta_phase). In case of a real mixing, I think you have to make some experiments to see the behaviour. The LO input and RF input will affect the DC level differently. After a certain level, LO level will not change the DC level much. However, RF level will always affect the DC level.