PLL for MIMO front-end, radio direction finder

[maniana]

I am looking for a solution for MIMO RF front-end.
Normal PLL will lock the RF to the reference but if you have several PLLs using the same reference the RF frequencies will have a random phase (RF to RF).
What I need is a PLL chip or a few of them that lock the RF frequency to the reference and I need the generated RF frequencies to be in phase with each other.
The first idea was to split the RF signal into several paths, but in this case all front-ends can only work at the same frequency.
My preference is to be able to run some of the front-ends at different frequencies. However when I tune all the front-ends to the same RF frequency I want all the RF phases to be the same. We are planning to have 5-7 antennas. RF frequency range DC to as high as possible, however for now we don't need more than 1GHz. One chip doesn't have to cover the whole range.
Can anyone suggest a solution?

 

[biff44]

the easies thing would be to use one PLL, and split the signal using phase matched cables for each receiver.

You can use independent DDS synthesizers running off of the same reference (after you take the phase differences out) and use a reset to each DDS to restart each at the same phase everytime you change frequency.

Similarly, you could use a PLL with a set of dividers that are resettable also.

A different approach would to not worry abot the receiver LOs matching in phase, just making them stable over time. Then injecting a test signal into each front end and measuring the phase to use as a calibration correction