DAC IOUT Amplitude | DAC IOUT Common Mode Current | VOUT Amplitude |
---|---|---|
7.8mAP-P | –6.2mA | 2.1VRMS |
Many high-performance audio digital-to-analog converters (DACs) feature a current output that must be converted into a voltage output for use with audio amplifiers. In premium automotive audio applications, for example, it is critical that the DAC signal-to-noise ratio (SNR) and total harmonic distortion plus noise (THD+N) performance is not compromised by the current-to-voltage (I-V) output stage.
The fC of the second stage is calculated with the following equation:
Using C1 = 4.7nF and C2 = 10nF, the fC of the first stage is approximately 44.2kHz and the fC of the second stage is approximately 66.3kHz.
where
where
The simulation shows that the 7.8mAP-P differential input current results in an approximately 6VP-P output, or 2.1VRMS.
The filters created by the two amplifier stages have a –3dB corner frequency of approximately 32.1kHz. This attenuates out-of-band noise from the output, while not affecting the audible range (20Hz to 22kHz).
The following simulation shows the benefit of having the majority of the gain of the circuit in the first stage. The two curves were generated by the same circuit with different resistor values, but resulting in the same total gain. The green line has a higher gain in the first stage, but lower total noise.
Device | Key Features | Link | Other Possible Devices |
---|---|---|---|
PCM1794A-Q1 | 24-bit, 192-kHz sampling, advanced segment, audio stereo digital-to-analog converter | 132dB, 24-bit, 192-kHz advanced Segment, Audio Stereo Digital-to-Analog Converter | Audio DACs |
OPA1612 | Ultra-low noise, ultra-low distortion, high-performance, bipolar-input audio operational amplifier | SoundPlus™ Audio Operational Amplifier with 1.1nV/√Hz Noise, Low THD and Precision | Audio Op-Amps |
Texas Instruments, HiFi Audio circuit design, application report
Texas Instruments, SBAM413 circuit, simulation files
Texas Instruments, Precision DAC Learning Center, portfolio overview
Texas Instruments, Audio DACs, portfolio overview
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