AK2400 Datasheet, PDF (30/52 Pages) Asahi Kasei Microsystems – High integrated receiver for PMR-LMR

[AK2400]
Block Diagram (PLL SYNTH)
The AK2400 is a Delta-Sigma Fractional-N PLL (Phase Locked Loop) frequency synthesizer with a
frequency switching function, covering a wide range of frequencies from 10 to 1000MHz. This product
consists of an 18-bit Delta-Sigma modulator, a low-noise phase frequency comparator, a highly accurate
charge pump, a reference divider, dual-module prescaler (P/P+1) and frequency offset adjustable circuits.
An excellent PLL can be achieved by combining this synthesizer with the external loop filter and VCO
(Voltage Controlled Oscillator). The operating supply voltage is from 2.7 to 5.5V; and the charge pump and
serial interface can be driven by individual supply voltages.
REFIN
R COUNTER
8bit
1.8V
PHASE
FREQENCY
DETECTOR
NUM + OFFSET
ΔΣ
18bit
INT
SUM
N DIVIDER
PULSE
SWALLOW
COUNTER
RFINP
+
RFINN
-
PRESCALER
4/5, 8/9,16/17
LOCK DETECT
CHARGE PUMP 1
CHARGE PUMP 2
(For Fast Lock Up)
FAST
COUNTER
13bit
Figure 9 Block Diagram (PLL SYNTH)
BIAS3
CP
CPZ
SWIN
LD
014008989-E-01
30
2015/4