**AD660ANZ: Key Specifications, Functional Overview, and Application Circuits**
The **AD660ANZ** is a monolithic, software-programmable, dual-channel **Tuned Intermediate Frequency (TIF)** receiver subsystem from Analog Devices. It integrates a complete signal path for processing low-level analog signals, making it a cornerstone component in sophisticated communication and measurement systems where precision and programmability are paramount.
### **Key Specifications**
The performance of the AD660ANZ is defined by a set of impressive electrical characteristics:
* **Architecture:** Dual-Channel, Tuned IF-to-Digital Receiver.
* **Resolution:** **14-bit** digital output for each channel, ensuring high-resolution data conversion.
* **Sampling Rate:** **Up to 20 MSPS** (Mega Samples Per Second), enabling the processing of high-frequency signals.
* **Input Bandwidth:** **40 MHz**, suitable for a wide range of intermediate frequencies.
* **Dynamic Performance:** Excellent **Spurious-Free Dynamic Range (SFDR)** and **Signal-to-Noise Ratio (SNR)**, critical for distinguishing wanted signals from noise and distortion.
* **Programmable Gain:** On-chip **Programmable Gain Amplifiers (PGAs)** allow for signal level optimization, enhancing dynamic range.
* **Digital Filtering:** Integrated **decimating filter** with programmable decimation rates (from 4x to 256x), which simplifies anti-aliasing and reduces the data rate for downstream processing.
* **Power Supply:** Typically operates on **+5V and -5.2V** supplies.
* **Package:** Offered in a **28-lead PDIP (Plastic Dual-In-Line Package)**, which is suitable for prototyping and a wide range of applications.
### **Functional Overview**
The AD660ANZ is far more than a simple analog-to-digital converter (ADC). Its integrated architecture provides a highly streamlined solution for digitizing bandpass signals. Each channel consists of:
1. **Track-and-Hold (T/H) Amplifier:** Acquires the analog input signal rapidly and holds it steady for conversion.
2. **Programmable Gain Amplifier (PGA):** Amplifies weak input signals to make full use of the ADC's dynamic range. The gain is set via a serial interface.
3. **14-Bit ADC:** The core component that converts the held analog voltage into a digital word.
4. **Digital Decimating Filter:** This is a key feature. It acts as a very sharp **digital bandpass filter**, centered at one-fourth of the sampling clock frequency (fCLK/4). It rejects out-of-band signals and noise while simultaneously reducing the output data rate, easing the load on the connected digital processor (e.g., a DSP or MCU).
The device is controlled via a serial port, which is used to set parameters like gain, power-down modes, and output format.
### **Application Circuits**
The AD660ANZ excels in applications that require the extraction of a specific frequency band from a wider spectrum. Its typical application circuit involves:
* **Antialiasing Filtering:** While the digital filter handles sharp bandpass selection, a simple, passive low-pass or bandpass filter is often used at the analog input to prevent higher-frequency aliases from being sampled.
* **Clock Driver:** A high-quality, low-jitter clock source is essential for driving the AD660ANZ's sampling clock input, as jitter directly impacts dynamic performance.
* **Digital Interface:** The digital output lines (14 bits per channel) and control pins (SDATA, SCLK, CS) are connected directly to a digital signal processor or microcontroller.
* **Power Supply Decoupling:** Proper decoupling with capacitors close to the power supply pins is critical to maintain stability and achieve specified performance. The datasheet provides specific layout and decoupling recommendations.
**Primary application areas include:**
* **Communication Systems:** **Software-Defined Radio (SDR)** receivers, digital beamforming, and cellular base stations for channel selection and digitization.
* **Sonar and Radar Processing:** For beamforming and signal analysis in multi-channel array systems.
* **Instrumentation:** **Spectrum analyzers** and network analyzers where precise, programmable frequency selection is required.
* **Medical Imaging:** Array processing in advanced ultrasound equipment.
**ICGOOODFIND:** The AD660ANZ is a highly integrated, system-level component that dramatically simplifies the design of complex IF sampling systems. Its combination of **dual 14-bit ADCs, programmable gain, and on-chip digital filtering** provides a powerful, compact solution for communication, defense, and instrumentation applications, reducing component count and design time while delivering high performance.
**Keywords:** Software-Defined Radio (SDR), 14-bit ADC, Digital Decimating Filter, Programmable Gain Amplifier (PGA), Tuned IF Receiver
