DATA SHEET • SKY72310 FREQUENCY SYNTHESIZER

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

200705E • Skyworks Proprietary and Confidential information • Products and Product Information are Subject to Change Without Notice • July 30, 2008

11

Table 3. Multiplexer Output

Multiplexer Output Select

(Bit 8)

Multiplexer Output Select

(Bit 7)

Multiplexer Output Select

(Bit 6)

Multiplexer Output

(Mux_out, Pin 24)

0

0

0

Reference Oscillator

0

0

1

Unused

0

1

0

0

1

1

Unused

1

0

0

1

0

1

Serial data out

1

1

0

Serial interface test output

1

1

1

Unused

A3

A2

A1

A0

11

10

9

8

7

6

5

4

3

2

1

0

1

0

0

0

0

00

0

X

X

Reserved Bits

Modulation Data Magnitude Offset

Modulation Data Input Select

Modulation Address Disable

C1425

Figure 11. Modulation Control Register (Write Only)

• Synthesizer Mode = One-bit flag to power down the ∆Σ

modulator and fractional unit. When this bit is cleared, the

synthesizer is in fractional-N mode. When this bit is set, the

synthesizer is in integer-N mode.

• Synthesizer ∆Σ Fractionality = One-bit flag to configure the size

of the

∆Σ modulator. This has a direct effect on power

consumption, and on the level of fractionality and step size.

When this bit is cleared, the

∆Σ modulator is 18-bit with a

bit is set, the

NOTE: There are no special power-up sequences required for the

SKY72310.

• Multiplexer Output Selection = Three-bit value that selects

which internal signal is output to the Mux_out pin. The following

internal signals are available on this pin:

− Reference oscillator: F

ref

− Divided reference (post-reference frequency divider): F

ref_main

− Phase detector frequency (post-frequency divider): F

pd_main

− Serial data out for loop-back and test purposes

Refer to Table 3 for more information.

• Mux_out Pin Tri-State Enable = One-bit flag to tri-state the

Mux_out pin. When this bit is cleared, the Mux_out pin is

enabled. When this bit is set, the Mux_out pin is tri-stated.

The Modulation Control Register is used to configure the

modulation unit of the main synthesizer. The modulation unit adds

or subtracts a frequency offset to the selected center frequency at

which the main synthesizer operates. The size of the modulation

data sample, controlled by the duration of the CS signal, can be

from 2 to 12 bits wide to provide from 4 to 4096 selectable

frequency offset steps.

The modulation data magnitude offset selects the magnitude

multiplier for the modulation data and can be from 0 to 8. As

shown in Figure 11, the values to be loaded are:

• Modulation Data Magnitude Offset = Four-bit value that

indicates the magnitude multiplier (m) for the modulation data

samples. Valid values range from 0 to 13, effectively providing a

• Modulation Data Input Select = One-bit flag to indicate the pin

on which modulation data samples are serially input when the

CS signal is between 2 and 12 bits long. When this bit is

cleared, modulation data samples are to be presented on the