ADF4377

ADF4377 IIO Wideband Synthesizer with Integrated VCO Linux Driver.

Supported Devices

Evaluation Boards

This driver supports the

Description

The ADF4377 is a high performance, utlralow jitter, dual output integer-N phased locked loop (PLL) with integrated voltage controlled oscillator (VCO) ideally suited for data converter and mixed signal front end (MxFE) clock applications. The high performance PLL has a figure of merit of -239 dBc/Hz, ultralow 1/f Noise and a high phase frequency detector (PFD) frequency that can achieve ultra-low in-band noise and integrated jitter. The ADF4377’s fundamental VCO and output divider generate frequencies from 800 MHz to 12.8 GHz. The ADF4377 integrates all necessary power supply bypass capacitors, saving board space on compact boards.

For multiple data converter and MXFE clock applications, the ADF4377 simplifies clock alignment and calibration routines required with other clock solutions, by implementing:

automatic reference to output synchronization,
extremely well match reference to output delays across process, voltage, and temperature
jitter free reference to ouput delay adjustment capability

These features allow for predictable and precise multi-chip clock and SYSREF alignment. JESD204B and JESD204C subclass 1 solutions are supported by pairing the ADF4377 with an integrated circuit (IC) that distributes pairs of reference and SYSREF signals.

Source Code

Status

Source	Mainlined?
ADI tree	Yes

Files

Function	File
driver	adf4377.c
Documentation	adi,adf4377.yaml
ABI documentation	sysfs-bus-iio-frequency-adf4377

Adding Linux driver support

Kernel configuration

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig)

Note

The ADF4377 driver depends on SPI and selects REGMAP_SPI

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig)

Linux Kernel Configuration
    Device Drivers  --->
    <*>     Industrial I/O support --->
        --- Industrial I/O support
                 Frequency Synthesizers DDS/PLL --->
                             *** Phase-Locked Loop (PLL) frequency synthesizers ***
                             <*> Analog Devices ADF4377 Microwave Wideband Synthesizer

Devicetree configuration

Example platform device initialization

The ADF4377 driver is a SPI bus driver and can be instantiated via device tree.

Required properties:

compatible: Should always be one of these:
- adi,adf4377
- adi,adf4378
reg: SPI chip select number.
clocks: a list of phandle, one for each entry in clock-names.
clock-names: Must include the following entry: ref_in

Optional properties:

chip-enable-gpios: chip-enable pin. clk1-enable-gpios: clock 1 output enable. clk2-enable-gpios: clock 2 output enable, ADF4377 only.

Example:

spi {
        #address-cells = <1>;
        #size-cells = <0>;
        frequency@0 {
            compatible = "adi,adf4377";
            reg = <0>;
            spi-max-frequency = <10000000>;
            clocks = <&adf4377_ref_in>;
            clock-names = "ref_in";
        };
    };

Driver testing

Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.

analog:/sys/bus/iio/devices/iio:device0# cd /sys/bus/iio/devices/
root@analog:/sys/bus/iio/devices# ls
iio:device0
root@analog:/sys/bus/iio/devices#

root@analog:/sys/bus/iio/devices# cd iio\:device0
root@analog:/sys/bus/iio/devices/iio:device0# ls -l
total 0
-r--r--r-- 1 root root 4096 sep  4 14:05 dev
-rw-r--r-- 1 root root 4096 sep  4 14:05 out_altvoltage0_frequency
-r--r--r-- 1 root root 4096 sep  4 14:05 name
lrwxrwxrwx 1 root root    0 sep  4 14:05 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/adf4377@0
drwxr-xr-x 2 root root    0 sep  4 14:05 power
lrwxrwxrwx 1 root root    0 sep  2 17:46 subsystem -> ../../../../../../../../bus/iio
-rw-r--r-- 1 root root 4096 sep  2 17:46 uevent

root@analog:/sys/bus/iio/devices/iio:device0#

Identify the device

root@analog:/sys/bus/iio/devices/iio:device0# cat name
adf4377

Read frequency

root@analog:/sys/bus/iio/devices/iio:device0# cat out_altvoltage0_frequency
1000000000

Set frequency

root@analog:/sys/bus/iio/devices/iio:device0# echo 1000000000 > out_altvoltage0_frequency
root@analog:/sys/bus/iio/devices/iio:device0# cat out_altvoltage0_frequency
1000000000

Muxout configuration

Configure the mux output with the optional adi,muxout-select Devicetree string. Supported values are high_z, lock_detect, muxout_low, f_div_rclk_2, f_div_nclk_2 and muxout_high; the default is high_z.