HP (Hewlett-Packard) HP 85660B ユーザーズマニュアル

The 

 YTO Phase Detector compares the frequency and phase of the 

 Sampler

IF signal to the output of the A10 

 Synthesizer Loop. The resultant error signal is

integrated, amplified, and applied to the A21 FM Coil Driver where it is routed to either the

main coil (dc path) or FM coil (ac path) of the 

 YTO. This tunes the YTO frequency

the proper amount in the proper direction to maintain phase lock.

The output of the 

 Sampler (IF IN) is passed through a 70 MHz LPF to remove any

unwanted frequencies which may have been introduced during the sampling process.

Each of the two input signals (IF IN and 

 IN) are passed through a limiter to

establish ECL signal levels. Each signal is then divided by two before being applied to the
phase/frequency detector. This lowers the frequency at which the detector must operate.

The two input signals (IF IN and 

 IN), after being divided by two, are applied to Phase

Frequency Detector U3. The function of U3 is to output a pulse which is related to the phase
difference of the two input signals. The width of this pulse is directly proportional to the
amount of phase difference. If the IF signal leads the 

 signal, a negative pulse appears at

U3 pin 3 

 the width of which is proportional to the amount of phase difference. If the

 signal leads the IF signal, a negative pulse appears at U3 pin 12 (TP2). In each case,

the other output is an ECL high (approximately -0.6 V). If the inputs are in phase, one of
the detector outputs is an ECL high (approximately -0.6 V) with narrow negative spikes and
the other just an ECL high. The detector outputs are averaged in the 1.5 MHz LPF before
being applied to the differential amplifier.

The detector outputs are applied to Differential Amplifier Q4. The output of this differential
amplifier is directly related to the phase difference of the IF IN and 

 IN signals.

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