Sasi Kumar Arunachalam

Integrated Class-D Audio Amplifier With 95% Efficiency and 105 dB SNR

An integrated ultralow EMI Class-D amplifier with a feed-forward ADC and feedback filters is demonstrated in a 180 nm CMOS and wire-bonded package. Circuit and architecture techniques, which enable 1.75 W into an 8 Ohm speaker, 105 dB SNR, 95% efficiency, 0.004% THD+N, and 15.4 dB margin beyond the EN55022 Class-B standard, are discussed.

Integrated Pop-Click Noise Suppression, EMI Reduction, and Short-Circuit Detection for Class-D Audio Amplifiers

Circuit techniques that overcome practical noise, reliability, and EMI limitations are reported. An auxiliary loop with ramping circuits suppresses pop-and-click noise to 1 mV for an amplifier with 4 V-achievable output voltage. Switching edge rate control enables the system to meet the EN55022 Class-B standard with a 15 dB margin. An enhanced scheme detects short-circuit conditions without relying on overlimit current events.

A 62mW stereo class-G headphone driver with 108dB dynamic range and 600µA/channel quiescent current

Mobile and portable devices like smartphones and tablets require headphone drivers that consume the lowest possible levels of quiescent current while operating directly from available battery voltages. Key headphone performance parameters for these devices are high dynamic range, high output power and low pop-and-click noise. This paper demonstrates a class-G headphone driver with 600μA/channel quiescent current that operates over a 2.95 to 4.5V supply range, which is compatible with Li-Ion batteries. This headphone driver achieves 108dB dynamic range, 62mW output power and 50μV pop-and-click noise.

An 8Ω, 1.75W, 95% efficiency, 0.004% THD+N Class-D amplifier with a feed-forward ADC and feedback filters

An integrated ultralow EMI Class-D amplifier with a feed-forward ADC and feedback filters is demonstrated in a 180 nm CMOS and wire-bonded package. Circuit and architecture techniques, which enables 1.75W into an 8 Ohm speaker, 105 dB dynamic range, 95% efficiency, 0.004% THD+N, and 15.4 dB margin beyond the EN55022 Class B standard, are discussed.

Circuit techniques to overcome Class-D audio amplifier limitations in mobile devices

Circuit techniques to overcome practical noise, reliability, and EMI limitations are reported. An auxiliary loop with ramping circuits suppresses pop-and-click noise to 1 mV for an amplifier with 4V achievable output voltage. Switching edge rate control enables the system to meet the EN55022 Class-B standard with a 15 dB margin. An enhanced scheme detects short-circuit conditions without relying on over-limit current events.

A 32-channel front-end for wireless HID using inverse-STF pre-filtering technique

A 32-channel front-end circuit for wireless Human Interface Devices (HID) is described. The front-end incorporates a Sigma-Delta ADC combined with an inverse-STF pre-filtering technique to achieve 10.8 ENOB at a conversion rate of 7.5µs per channel. Chopping and digital calibration are employed to achieve an offset voltage < 850µV and gain error < 0.17%. The HID front-end measures single-ended rail-to-rail inputs with 1.62V to 3.63V supply range, occupies 0.28mm2 in 65nm CMOS and consumes 1.8mW from 1.2V supply.