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RFFC2071A/2A

DS140110

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or customerservice@rfmd.com.

External Modulation

The RFFC2071A and RFFC2072A fractional-N synthesizer can be used to modulate the frequency of the VCO. There are two

dedicated registers, EXT_MOD and FMOD, which can be used to configure the device as a modulator. It is possible to modulate

the VCO in two ways:

1.Binary FSK

The MODSETUP bits in the EXT_MOD register are set to 11. GPO3 is then configured as an input and used to control the signal

frequency. The frequency deviation is set by the MODSTEP and MODULATION bits in the EXT_MOD and FMOD registers respec-

tively.

The modulation frequency is calculated according to the following formula:

2.Continuous Modulation

The MODSETUP bits in the EXT_MOD register are set to 01. The frequency deviation is set by the MODSTEP and MODULATION

bits in the EXT_MOD and FMOD registers respectively. The VCO frequency is then changed by writing a new value into the MOD-

ULATION bits, the VCO frequency is instantly updated. An arbitrary frequency modulation can then be performed dependant

only on the rate at which values are written into the FMOD register.

The modulation frequency is calculated according to the following formula:

Programming Information

The RFFC2071A and RFFC2072A share a common serial interface and control block. Please refer to the register map and pro-

gramming guides which are available for download from http://rfmd.com/products/IntSynthMixer/.

Evaluation Boards

Evaluation boards for RFFC2071A and RFFC2072A are provided as part of a design kit, along with the necessary cables and

programming software tool to enable full evaluation of the device. The evaluation board has been configured for wideband

operation. The mixer inputs and outputs are connected to wideband transmission line transformer baluns. Design kits can be

ordered from www.rfmd.com or from local RFMD sales offices and authorized sales channels. For ordering codes please see

“Ordering Information” on page 22. For further details on how to set up the design kits please refer to the user guide which can

be downloaded from http://rfmd.com/products/IntSynthMixer/.

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