PS2500 datasheet(25/28 Pages) ETC2

25 / 28 page

PS2500 2.2 GHz Fractional-N Frequency Synthesizer

- 25 -

Philsar Semiconductor Inc.

146 Colonnade Road S.

Nepean, Ontario, Canada

K2E 7Y1

Tel: 613-274-0922

Fax: 613-274-0915

www.philsar.com

PMP-001-DS2 V1.2

• Mux_out Pin Tri-State Enable = 1-bit value for tri-stating the Mux_out pin. When this bit is 0, the

Mux_out pin is enabled. When this bit is 1, the Mux_out pin is tri-stated.

Figure 12: Hex8 Modulation Control Register (Write only)

This register is used to configure the modulation unit of the main synthesizer.

The modulation unit provides for adding or subtracting a frequency offset to the selected center frequency

at which the main synthesizer is operating. The size of the modulation data sample, controlled by the

duration of /CS, can be from 2 to 12 bits wide, to provide from 4 to 4096 selectable frequency offsets steps.

The modulation data magnitude offset selects the magnitude multiplier for the modulation data and can be

from 0 to 8.

Values to be loaded are:

Modulation Data Magnitude Offset = 4-bit value indicating magnitude multiplier (m) for the modulation

data samples. Valid values range from 0 to 13, effectively providing a 2m multiplication of the modulation

data sample.

Modulation Data Input Select = 1-bit value indicating the pin on which modulation data samples are

serially input when /CS is between 2 and 12 bits long. When this bit is 0, modulation data samples are to be

presented on the Data pin. When this bit is 1, modulation data samples are to be presented on the Mod_in

pin. For more details, please refer to section “Direct Digital Modulation” on page 10.

Modulation Address Disable = 1-bit value indicating the presence of the address as modulation data

samples are presented on either the Mod_in or Data pins. When this bit is 0, address is presented with the

modulation data samples (i.e. all transfers are 16 bits long). When this bit is 1, no address is presented with

the modulation data samples (i.e. all transfers are 2 to 12 bits long). For more details, please refer to section

“Direct Digital Modulation” on page 10.

Reserved Bits

Modulation Data Magnitude Offset

Modulation Data Input Select

Modulation Address Disable

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