Some measurements

A project log for Microwave synthesizer 4-7GHz

Microwave synthesizer - experiments with microwave black magic

michal777michal777 02/16/2020 at 20:410 Comments

1. VCOs - they work (after some tuning, and replacing one transistor)

2. Amplifiers (2-3.5GHz in three ranges) - they are ok, VCOs output signal is higher than expected so maybe I need one instead of two amplifiers or I must add some attenuators

3. Atternuators - they work, attenuation range about 10dB (not much but close enough to simulations)

4. Doublers - they work (2nd harmonic much above the input), no accurate measurements done yet

5. PIN switch - it does something but I can't test it separately with the current PCB layout (maybe I'll attempt it later)

6. Filters - the lowest band looks fine, it's hard to test the others (measurements errors can be bad at so high frequency and currently I can't go above 6GHz)

7. Output amplifier first part (3 stage) - not good, hard to test, seems to be unstable but possibly the problem is caused by test setup (depending of arrangement of coax cables connected to PCB it oscillates or not); possibly it can be useable after some tuning

8. Output amplifier the second part (2 way) - part1+part2 output amplifier is much more unstable than the first part only so I'll skip the two-way amplifier for now; it's bad because of huge out of band gain, especially about 2GHz where it usually oscillates.

So the plan for now is to put all together, without the final amplifier.