LMX2364 National Semiconductor Corporation, LMX2364 Datasheet - Page 29

• Manufacturer Part Number: LMX2364
• Description: 2.6 Ghz Pllatinum Fractional Rf Frequency Synthesizer With 850 Mhz Integer If Frequency Synthesizer
• Manufacturer: National Semiconductor Corporation

Programming Description
2.6.3 RF_CP[1:0] — Charge Pump Gain, RF Synthesizer
The RF_CP word is used to control the charge pump gain for the RF synthesizer. Four different CP gains are supported ranging
from 1 to 16 mA. Note that when RF FastLock mode is enabled and the synthesizer is operating in the FastLock state, the charge
pump gain is controlled by the RF_CPF[1:0] control word. Higher charge pump currents yield slightly better phase noise, but lead
to larger loop filter capacitors and slightly higher current consumption in cases where the comparison frequency is very high.
2.6.4 RF_CPP — Phase Detector Polarity, RF Synthesizer
This bit controls the polarity of phase detector for the RF synthesizer. It should be set to one when the chosen RF VCO has
positive tuning gain, and zero when the tuning gain is negative.
2.6.5 RF_P — Prescaler, RF Synthesizer
The RF synthesizer utilizes a selectable quadruple modulus prescaler. RF_P selects between the 8/9/12/13 prescaler and the
16/17/20/21 prescaler as described in the table below.
2.6.6 RF_RST — Counter Reset, RF Synthesizer
The RF Counter Reset enable bit when activated (RF_RST = 1) allows the reset of both the RF N and RF R dividers. Upon
powering up, the N counter resumes counting in "close" alignment with the R counter. The maximum error is one prescaler cycle.
RF_CP[1:0]
RF_P[1:0]
(Continued)
0
1
2
3
0
1
Charge Pump Current
Selected Prescaler
29
16 (16/17/20/21)
8 (8/9/12/13)
16 mA
1 mA
4 mA
8 mA
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