S1A0903X01-Q0R0 Samsung Electronics, S1A0903X01-Q0R0 Datasheet - Page 46

• Manufacturer Part Number: S1A0903X01-Q0R0
• Description: AM/FM 1 Chip Tuner with PLL
• Manufacturer: Samsung Electronics

S1A0903X01
AM/FM 1CHIP TUNER WITH PLL
TERMONOLOGY
DeadZone
PFD has to detect subtle phase error and makes phase error signal. There is a region that PFD doesn't make any
phase error pulse due to the propagation delay or other factors, which is called Deadzone.
Performance of PLL frequency synthesizer depends on the width of DeadZone
The characteristic of PFD is not ideal A(Figure. 18) but curved B(Fig. 18) because PLL frequency synthesizer
operates on reference signal just like a LPF(low pass filter)
The cause of Deadzone is that PFD doesn't generate phase error signal even though there is a phase error
between reference frequency and VCO divided by N. In general deadzone has several nano seconds width.
To implement a high S/N ratio system, the width of Deadzone is as narrow as possible. But, RF leakage in
MIXER block comes into VCO, which causes be a noise.
V
A
B
(ns)
DeadZone
Figure 18. PFD Characteristic
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