StellamarXilinxXC3S400AN Digital ADC Audio Evaluation Solution

Stellamar’s digital ADC uses Xilinx’s XC3S400AN FPGA, with 50% lower average power consumption, 50% lower area, very low operating voltage, up to 14 effective bits, 14-bit 500Hz SNR of 90dB, digital dictionary output, digital Test, oversampling, no missing codes, very low offset drift, can be used in harsh environments. Target applications in speech, consumer and industrial sensors, low power handheld devices and military, space and aerospace. This article introduces Main features of digital ADC, digital ADC audio evaluation board frame diagram, circuit diagram and bill of materials.

The Digital ADC is a digital core which provides analog functionality with all the benefits of a digital design process: shorter design cycles, lower risk, established design and layout tools, digital test methodology, and portability across process technologies.

The design is implemented with a small number of digital gates and only an LVDS input cell, a digital output cell and a handful of passive external components

The ADC provides up to 12 effective bits and up to 15 kHz of bandwidth making it ideal fit for both low frequency sensors and high-quality voice.

The benefits of the digital implementation include low voltage and low power process technologies where it excels in portable applications.

Alternative digital process technologies enable the Digital ADC to be used in high reliability and radiation hard environments where analog implementations are problematic.

Digital ADC main features:

 On average 50% less power1

 On average 68% smaller area1

 Very low supply voltages

 Up to 14 effective bits

 Bandwidth

o 14 bits, 500 Hz with SNR 90 dB

o 12 bits, 4 kHz with SNR 72 dB

o 12 bits, 15 kHz with SNR 68 dB

 Process Technology Independent

 Digital Layout

 Digital Testing

 Oversampling

 No missing codes

 Extremely low offset drift

 Suitable for Rad-Hard environments

Digital ADC target applications:

 Voice

 Sensors (Consumer and Industrial)

 Low Power portable

 Military, Space and Avionics

Digital ADC Audio Evaluation Board

Digital ADC Audio Evaluation Board

The Stellamar Digital ADC audio evaluation board provides a platform that contains two separate implementations of the Digital ADC targeted at audio applications. The ADC implementation is selected by switch 1 in SW1.

0) 11-bit ADC with a 5 kHz bandwidth. This ADC may be used for voice signals where higher frequency signals are not required, enabling a smaller digital design.

1) 10-bit ADC with a 20 kHz bandwidth. This ADC provides a higher bandwidth that is suitable for musical signals, but has a larger digital design.

Figure 1. Digital ADC Audio Evaluation Board Outline Drawing

Figure 2. Digital ADC Audio Evaluation Board Block Diagram

Figure 3. Digital ADC Audio Evaluation Board Circuit Diagram (1)

Figure 4. Digital ADC Audio Evaluation Board Circuit Diagram (2)
Digital ADC Audio Evaluation Board Bill of Materials:

For details, see:
http://www.stellamar.com/docs/Audio_EVB_User_Guide.pdf