MLX71122_16 datasheet(22/59 Pages) MELEXIS

22 / 59 page

MLX71122

300 to 930MHz FSK/FM/ASK Receiver

Datasheet

REVISION 014 – AUGUST, 2016

Page 22 of 59

390 10 71122 01

List of Mathematical Acronyms

divider ratio of the swallow counter (part of feedback divider)

frequency at the feedback divider output

(x)

floor

The floor function gives the largest integer less than or equal to x.

For example, floor(5.4) gives 5, floor(-6.3) gives -7.

PFD

PFD frequency in locked state



reference frequency of the PLL

frequency of the crystal reference oscillator

VCO

frequency of the VCO (equals the LO1 signal of the first mixer)

tot







total divider ratio of the PLL feedback path

divider ratio of the program counter (part of feedback divider)

LO2

LO2DIV divider ratio, to derive the LO2 signal from LO1 (N1 = 4 or 8)

divider ratio of the prescaler (part of feedback divider)

divider ratio of the reference divider R

3.2.1. Pulse Swallow Counter

The programmable feedback divider of the PLL is based on a pulse-swallow topology. Fig. 5 depicts its

implementation, consisting of a dual-modulus prescaler, an RS latch and two programmable counters.

Fig. 5

Pulse Swallow Counter Topology

During one cycle of fFB the prescaler begins the operation by dividing by P+1 until the swallow counter A is

full. The RS latch is then set and changes the prescaler modulus to P (via the modulus control signal MC)

and disables the swallow counter. The division process continues until the program counter N is full and

the RS latch is reset.

VCO

P / P+1

Program

Counter

Swallow

Counter

Modulus Control

Signal (MC)

Dual Modulus

Prescaler

PFD

LATCH

FB =

VCO

N P + A

Mode

P+1

MLX71122 Datasheet(PDF) 22 Page - Melexis Microelectronic Systems

MLX71122 Datasheet(HTML) 22 Page - Melexis Microelectronic Systems

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

Datasheet Download

Link URL