As the heart of many instrumentation and control systems, digital-to-analog converters (DACs) play a key role in determining system performance and accuracy. This article looks at a new precision, fast-settling, voltage-output 16-bit DAC and shows some ideas for buffering the outputs of high-speed complementary current-output DACs that can rival transformer performance.
Direct digital synthesis (DDS) technology is used to generate and modify high-quality waveforms in a broad range of applications in such diverse fields as communications, defense, medicine, industry, and instrumentation. This article provides an overview of the technology, describes its strengths and limitations, looks at some application examples, and showcases some significant new products.
This article describes how two synchronized DDS channels can implement a zero-crossing FSK or PSK modulator. In phase-coherent radar systems, zero-crossing switching reduces the amount of post processing needed for target signature recognition; and zero-crossing switching reduces PSK spectral splatter. Here, the AD9958 two-channel complete DDS is used to switch at the zero crossing.
Traditional gain-selectable amplifiers use switches in the feedback loop to connect resistors to an amplifier, but the switch resistance degrades the noise performance of the amplifier, adds significant capacitance on the inverting input, and contributes to nonlinear gain error. This article presents a gain-selectable amp that uses an innovative switching technique that preserves the noise performance while reducing the nonlinear gain error.