**AD977BRSZ: A Comprehensive Technical Overview of the 14-Bit, 125 MSPS Dual-Channel TxDAC+® Digital-to-Analog Converter**

The **AD977BRSZ** represents a high-performance member of Analog Devices' renowned **TxDAC+® family**, a series of digital-to-analog converters (DACs) specifically engineered for demanding transmit signal chain applications. This device integrates two complete 14-bit DACs operating at up to **125 MSPS (Mega Samples Per Second)**, making it a cornerstone solution for communication systems, medical imaging, and instrumentation where high-speed, multi-channel signal generation is paramount.

**Architectural Innovation and Core Features**

At the heart of the AD977BRSZ lies a sophisticated segmented current-source architecture. This design is a hallmark of the TxDAC+ family, chosen for its superior dynamic performance—specifically its ability to minimize glitch energy and provide excellent spurious-free dynamic range (SFDR). Each of the two DAC cores is equipped with its own independent input data port, allowing for **precise dual-channel operation** with flexible interleaving or independent channel control.

A critical feature of this converter is its **integrated 1.2V reference**. This on-chip reference circuitry enhances system reliability by minimizing the number of external components required and ensures stable performance over temperature and supply variations. For applications demanding higher precision, the internal reference can be overridden by an external one.

The analog output is provided as a differential current, which is typically converted into a single-ended voltage using an external operational amplifier. The full-scale output current is programmable via a single resistor, offering designers significant flexibility to optimize for dynamic range or power consumption. The device operates from a single **+3.3V or +5V supply**, with separate digital and analog supplies to mitigate noise from digital switching.

**Key Performance Parameters**

The AD977BRSZ is designed to excel in the frequency domain, a critical requirement for communications. It delivers exceptional **AC performance**, including:

* **High Spurious-Free Dynamic Range (SFDR)**: Typically 80 dBc at 1 MHz output, ensuring clean signal generation.

* **Low Glitch Impulse**: The segmented architecture results in very low glitch, reducing unwanted harmonic distortion.

* **Excellent Gain and Offset Matching**: The two channels are meticulously matched, which is vital for I/Q modulation or diversity transmission systems.

**Application Domains**

The combination of speed, resolution, and dual-channel integration makes the AD977BRSZ exceptionally versatile. Its primary applications include:

* **Communications Infrastructure**: As the key DAC in the transmit path of wireless base stations (e.g., 4G/LTE, 5G), driving I and Q modulators with precise, high-speed data.

* **Medical Ultrasound Imaging**: Generating the precise transmit pulses and beamforming signals needed for high-resolution imaging systems.

* **Instrumentation and Arbitrary Waveform Generators (AWG)**: Creating complex, high-frequency analog waveforms with high fidelity.

* **Quadrature Modulation**: The matched channels are ideal for generating the in-phase (I) and quadrature (Q) components required in digital up-conversion (DUC) systems.

**ICGOODFIND**

The **AD977BRSZ** stands as a testament to the maturity and performance of the TxDAC+ technology. Its **dual-channel, 14-bit resolution, and 125 MSPS speed** are seamlessly integrated into a single package, offering system designers a compact, reliable, and high-performance solution for complex signal generation tasks. Its **excellent dynamic performance and flexible interface** solidify its position as a go-to component for advanced digital transmission systems across multiple industries.

**Keywords:**

1. **Dual-Channel DAC**

2. **125 MSPS**

3. **TxDAC+®**

4. **Spurious-Free Dynamic Range (SFDR)**

5. **Digital-to-Analog Converter**