AD9680 no-OS Driver

See drivers/adc/ad9680 (doxygen) for the Doxygen documentation.

Supported Devices

AD9680

Overview

The AD9680 is a dual analog-to-digital converter (ADC) featuring JESD204B (Subclass 1) coded serial digital outputs and operates with 1.65W total power per channel at 1 GSPS (default settings). It offers exceptional dynamic performance with SFDR at 1 GSPS = 85 dBFS at 340 MHz, 80 dBFS at 1 GHz, and SNR at 1 GSPS = 65.3 dBFS at 340 MHz (AIN = −1.0 dBFS), 60.5 dBFS at 1 GHz (AIN = −1.0 dBFS). Additionally, it delivers ENOB = 10.8 bits at 10 MHz, DNL = ±0.5 LSB, INL = ±2.5 LSB, and Noise density = −154 dBFS/Hz at 1 GSPS.

Designed for sampling wide bandwidth analog signals of up to 2 GHz, the AD9680 is a dual, 14-bit, 1.25GSPS/1GSPS/820MSPS/500MSPS ADC that features an on-chip buffer and sample-and-hold circuit engineered for low power, small size, and ease of use. The device is optimized for wide input bandwidth, high sampling rate, excellent linearity, and low power in a small package, supporting multiple power supply configurations with 1.25V, 2.5V, and 3.3V dc supply operation and offering a flexible input range of 1.46Vp-p to 1.94Vp-p.

Applications

Communications
Diversity multiband, multimode digital receivers
- TD-SCDMA, W-CDMA, GSM, LTE
General-purpose software radios
Ultrawideband satellite receivers
Instrumentation
Radars
Signals intelligence (SIGINT)
DOCSIS 3.0 CMTS upstream receive paths
HFC digital reverse path receivers

Operation Modes

The AD9680 supports the following operation modes:

Normal Mode: Standard dual-channel ADC operation for signal acquisition.
Test Mode: Outputs predefined test patterns (PN9, PN23, ramp) for data path validation and debugging.
SYSREF Modes: Configurable SYSREF synchronization including none, one-shot, continuous, and monitor modes for JESD204B link alignment.

Device Configuration

Initialization Functions

The initialization functions form the foundation for configuring the AD9680 device. The ad9680_setup() function initializes SPI communication, verifies the chip identity, configures JESD204B settings, and confirms PLL lock status, while the ad9680_setup_jesd_fsm() function sets up and registers the JESD204B interface using the proper device parameters.

SPI Communication Functions

The SPI communication functions provide low-level access for register transactions over the Serial Peripheral Interface. The ad9680_spi_read() function retrieves the current value from a specified register, and the ad9680_spi_write() function writes new data to a designated register.

JESD204 Link Configuration Functions

The JESD204 link configuration functions are responsible for establishing and managing the high-speed serial interface required for data conversion. The ad9680_jesd204_link_init() function initializes the JESD204 link by setting critical link parameters, ad9680_jesd_enable_link() modifies registers to enable or disable the link, ad9680_jesd204_clks_enable() ensures that the link clocks are active, and ad9680_jesd204_link_enable() finalizes the activation sequence necessary for full link operation.

Test Mode Configuration Function

The test mode configuration function simplifies the process of activating diagnostic and validation routines. The ad9680_test() function configures the ADC's internal test mode and output format settings based on the supplied test mode parameter.

Device Removal Function

The device removal function is dedicated to proper deallocation of system resources when the AD9680 is no longer in use. The ad9680_remove() function handles the removal of the SPI descriptor and frees the internal device structure to ensure that memory leaks and communication issues do not occur.

Driver Initialization Example

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include "no_os_delay.h"
#include "no_os_spi.h"
#include "jesd204.h"
#include "no_os_util.h"
#include "ad9680.h"
#include "no_os_error.h"
#include "no_os_print_log.h"
#include "no_os_alloc.h"

struct ad9680_init_param init_param = {
    .spi_init = {
        .device_id       = 1,
        .max_speed_hz    = 1000000,
        .chip_select     = 1,
        .mode            = NO_OS_SPI_MODE_0,
        .platform_ops    = &xil_spi_ops,
        .extra           = &xil_spi_param,
    },
    .lane_rate_kbps      = 10000000,
    .jesd204_link = {
        .link_id         = 0,
        .sample_rate     = 1000000000,
        .sample_rate_div = 1,
        .jesd_encoder    = JESD204_ENCODER_8B10B,
        .sysref = {
            .mode        = JESD204_SYSREF_CONTINUOUS,
        },
    },
    .sampling_frequency_hz = 1000000000,
    .dcm                  = 1,
    .sysref_mode          = AD9680_SYSREF_CONT
};

struct ad9680_dev *device;
int32_t status;

status = ad9680_setup(&device, &init_param);
if (status < 0) {
    printf("AD9680 initialization failed.\n");
    goto error;
}

printf("AD9680 initialization successful.\n");

error:
    ad9680_remove(device);