6

NOTE: Other instruments can be used for the BB phase and amplitude mismatch

measurements, such as HP 4192A, impedance analyzer or other.

11. BB filters frequency response measurements. The BB filters’ frequency response can

be measured using the set up of steps 3 and 4 by sweeping the input IF frequency

from 285 to 275 MHz. Correspondingly, the BB output will have 0 to 10 MHz sweep.

If the IF input frequency is swept manually, the spectrum analyzer should be in

maximum hold mode. One marker should be placed into 10 to 100 KHz point as a

reference and another marker should be placed at the point where the frequency

response of the BB filter has a 3.0 dB drop. This represents the 3.0 dB corner

frequency of the BB filter. The same test can be conducted using a tracking generator

or network analyzer. In this case, an external I/Q modulator will be necessary to bring

BB signals back to the original input frequency range.