X-band downconverter.

As the input LNA was used industrial Vertex LXA-7550 (bought on e-bay). Technical spec.

Amplifier in need of modernization, which consists of gain reduction and replacement of a narrowband filter.

First, you must remove the original narrow-band filter. Instead, use a combination of two Mini-Circuit filters LFCN-8400 + HFCN-6010.

You must also add 14 dB pi-attenuator (consisting of 120-75-120 Ohm resistors):


The second part converter is made in a separate housing. Was designed circuitry:

Obtained a local oscillator following characteristics (pll width 350kHz, phase margin 60 deg, charge pump 2.5 ma):

Frequency: 6.305GHz

Phase noise:

100Hz -63dBc/Hz

1kHz -80dBc/Hz

10kHz -86dBc/Hz

100kHz -90dBc/Hz

1MHz -105dBc/Hz

Spoors +/- 13MHz <-83dBc

Screenshots phase noise measurements:

The final product may receive in the range of 7.25-8.45GHz and convert to 950-2150MHz.

Firmware, PCB full project and other see here >>>>>...........



-------------------------------- Added 9 Apr 2014 ---------------------------------