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ADF4153YCPZ-RL7 数据表(PDF) 10 Page - Analog Devices |
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ADF4153YCPZ-RL7 数据表(HTML) 10 Page - Analog Devices |
10 / 24 page ADF4153 Data Sheet Rev. F | Page 10 of 24 PHASE FREQUENCY DETECTOR (PFD) AND CHARGE PUMP The PFD takes inputs from the R counter and N counter and produces an output proportional to the phase and frequency difference between them. Figure 14 is a simplified schematic of the phase frequency detector. The PFD includes a fixed delay element that sets the width of the antibacklash pulse, which is typically 3 ns. This pulse ensures that there is no dead zone in the PFD transfer function and gives a consistent reference spur level. U3 CLR2 Q2 D2 U2 DOWN UP HI HI CP –IN +IN CHARGE PUMP DELAY CLR1 Q1 D1 U1 Figure 14. PFD Simplified Schematic MUXOUT AND LOCK DETECT The output multiplexer on the ADF4153 allows the user to access various internal points on the chip. The state of MUXOUT is controlled by M3, M2, and M1 (see Table 8). Figure 15 shows the MUXOUT section in block diagram form. DIGITAL LOCK DETECT R COUNTER DIVIDER LOGIC LOW DGND CONTROL MUX MUXOUT DVDD THREE-STATE OUTPUT N COUNTER DIVIDER ANALOG LOCK DETECT LOGIC HIGH s Figure 15. MUXOUT Schematic INPUT SHIFT REGISTERS The ADF4153 digital section includes a 4-bit RF R counter, a 9-bit RF N counter, a 12-bit FRAC counter, and a 12-bit modulus counter. Data is clocked into the 24-bit shift register on each rising edge of CLK. The data is clocked in MSB first. Data is transferred from the shift register to one of four latches on the rising edge of LE. The destination latch is determined by the state of the two control bits (C2 and C1) in the shift register. These are the 2 LSBs, DB1 and DB0, as shown in Figure 2. The truth table for these bits is shown in Table 5. Table 6 shows a summary of how the registers are programmed. PROGRAM MODES Table 5 through Table 10 show how to set up the program modes in the ADF4153. The ADF4153 programmable modulus is double buffered. This means that two events have to occur before the part uses a new modulus value. First, the new modulus value is latched into the device by writing to the R divider register. Second, a new write must be performed on the N divider register. Therefore, to ensure that the modulus value is loaded correctly, the N divider register must be written to any time that the modulus value is updated. Table 5. C2 and C1 Truth Table Control Bits C2 C1 Register 0 0 N Divider Register 0 1 R Divider Register 1 0 Control Register 1 1 Noise and Spur Register |
类似零件编号 - ADF4153YCPZ-RL7 |
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类似说明 - ADF4153YCPZ-RL7 |
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