Agilent Technologies 856290216 General PLL Troubleshooting, PLL Locked at Wrong Frequency

Table 11-5. Sampling Oscillator Test Frequencies

HP 8340A

CW Frequency (GHz)

6.067000

6.087000

6.110200

6.141000

4.710000

6.174000

6.193000

6.213000

6.066000

6.069000

6.247000

6.107000

3.912000

6.289000

6.321000

6.333000

HP 85633

Center Frequency (MHz)

2156.3

2176.3

2199.5

2230.3

799.3

2263.3

2282.3

2302.3

2155.3

2158.3

2336.3

2196.3

1.3

2378.3

2410.3

2422.3

Offset PLL	Counter Reading
Sampling Oscillator Freq	Sampler IF
(MHz)	(MHz)
285.000	82.000
286.364	73.364
287.500	72.700
288.462	83.308
288.889	87.778
290.000	84.000
290.909	83.909
291.667	88.000
292.500	76.500
293.478	94.044
294.444	63.667
295.000	88.000
296.000	64.000
296.471	63.118
297.000	84.000
297.222	91.333

General PLL Troubleshooting

The synthesizer section relies heavily on phase-locked loops (PLL). Typically, a faulty PLL is either locked at the wrong frequency or unlocked. The information below applies to troubleshooting these two classes of problems on a generalized PLL.

PLL Locked at Wrong Frequency

Numbers in the following text identify items in Figure 11-5:

w Any frequency errors at reference (1) will be multiplied by N/M on the PLL output.

w A sampler reference-frequency error (2) will be multiplied by its harmonic on the PLL output.

H A mixer reference-frequency error (3) produces the identical error on the PLL output.

w If divider input or output frequencies (4) are wrong, check for incorrect divide numbers and data controlling the dividers.

Synthesizer Section 1 I-13