1GHz to 10GHz analog switch/selector

[rfmw]

I need to delay an analog broadband signal (bandwidth from 1GHz to over 10GHz) from 0 to 6 ns. The delay can be in discrete steps, like 1ns (not higher).

The idea to create the delay is by using coax cables with different lengths and switching between them according to the desired delay.

What components to choose from, any other idea is also very welcomed.

Thanks,
rfmw

 

[jiripolivka]

Your problem will be quite difficult to solve. There are MMIC or PIN switches available but all are quite expensive. You will need to use such switches in pairs, to insert one coaxial delay section after another.

If you can find a suitable wideband antenna and allow some loss, I would try for instance to use a pair of wideband horns (there are 1-18 GHz such antennas available for EMC testing), then you can use the separation between them to adjust a desired delay (one nanosecond is 30 cm propagation delay in air).
You can locate such antennas side by side and use a flat or a corner reflector to adjust the delay (now the distance between the antennas and reflector can be zero to ~15 cm for 0-6 ns.

Murata offers ceramic delay lines in discrete units, try their products. I do not know if such delay blocks can meet your bandwidth, though.

Also, if you have time , you can use an "air" coaxial line like 25 cm long and insert wedge-like dielectric sections made of a high-k material. Using e.g. a deionized water with k~81 would give you 9-times longer delay than in air. I saw similar devices used as phase-shifters in the 1950's. The coaxial line was U-shaped and filled with deionized water so that its levels were slant in the line, to improve matching.

 

[biff44]

I would use two hittite hmc322lp4 switches, and 8 different lenths of transmission line: x, x +6ns/7, x + 2*6ns/7...+ x +6 ns. If you need tight tolerance, you will need some tuning pads along the lines, maybe even have to go with the chip version (unpackaged) of the switch.

Rich