The **AD9767** is a high-performance, dual-channel, 14-bit CMOS Digital-to-Analog Converter (DAC) manufactured by Analog Devices. It is part of the TxDAC® family, designed specifically for the transmit path of communication systems. --- ## 1. Key Specifications The following table summarizes the primary electrical and performance characteristics: | Parameter | Specification | | :--- | :--- | | **Resolution** | 14-Bit | | **Number of Channels** | 2 (Dual DAC) | | **Update Rate** | 125 MSPS (Mega Samples Per Second) | | **Supply Voltage** | 3.0 V to 3.6 V | | **Power Consumption** | ~380 mW (at 3.3V) | | **Interface** | Parallel (Twin 14-bit ports) | | **Package** | 48-lead LQFP | --- ## 2. Internal Functional Components The AD9767 architecture consists of several critical electronic stages: ### A. Dual DAC Cores The chip contains two independent 14-bit DACs. Each core uses a **segmented current source architecture**. This reduces glitch impulse and improves linearity compared to standard binary-weighted DACs. ### B. Internal Reference - The device includes an onboard **1.2V bandgap reference**. - It can also be driven by an external reference for higher precision applications. - The `REFIO` pin is used to bypass or supply this reference voltage. ### C. Digital Interface The AD9767 features two separate 14-bit wide parallel input ports. This allows for simultaneous data loading for both channels, which is critical for applications like **I/Q modulation**. ### D. Current Outputs The outputs are differential current outputs ($I_{OUTA}$ and $I_{OUTB}$). - **Full-scale current:** Typically adjustable from 2 mA to 20 mA using an external resistor ($R_{SET}$). - **Differential Output:** Helps in rejecting common-mode noise and reducing even-order harmonics. --- ## 3. Pin Configuration Overview Selected critical pins for electronic integration: | Pin Name | Type | Description | | :--- | :--- | :--- | | **DB13 - DB0** | Input | Digital Data bits (Port 1 and Port 2). | | **CLK1 / CLK2** | Input | Independent clock inputs for each DAC. | | **IOUTA / IOUTB** | Output | Differential current outputs for each channel. | | **FS ADJ** | Analog | Full-scale adjust; connects to $R_{SET}$ to determine max output current. | | **DVDD / AVDD** | Power | Separate Digital and Analog 3.3V supply rails. | --- ## 4. Typical Application Circuit When designing a PCB with the AD9767, the output is usually converted from current to voltage using a transformer (Balun) or an Operational Amplifier. ```text [Digital Controller] -> [AD9767 Pins DB0-DB13] | [AD9767 DAC Core] | [Differential Current Out] | [Low Pass Filter (LPF)] | [Transformer / Balun] -> [Single-Ended RF Out] ``` --- ## 5. Major Use Cases 1. **Communication Systems:** WCDMA, CDMA2000, and GSM base stations. 2. **I/Q Modulation:** Because it has dual channels, it is perfect for generating In-phase (I) and Quadrature (Q) signals. 3. **Signal Synthesis:** Arbitrary Waveform Generators (AWG) and Direct Digital Synthesis (DDS). 4. **Instrumentation:** High-speed medical imaging and automated test equipment. ---