Sherif Galal

A 60 mW Class-G Stereo Headphone Driver for Portable Battery-Powered Devices

A 60 mW 1.15 mA/channel Class-G stereo headphone driver primarily designed for demanding applications in mobile phones and other portable communication devices is described. The architecture of the driver has been chosen to overcome the various design challenges for audio amplifiers in a wireless environment. A high-order feed-forward loop topology provides high immunity to battery disturbance with extended correction range. In addition, a Class-G amplifier with a Class-AB/B driving stage improves the small-signal efficiency and extends music playback time. Implemented in 0.18 μm CMOS technology, the stereo headphone driver achieves a DR of 111 dB and PSRR of 120 dB at the GSM TDMA frequency of 217 Hz while occupying an area of 2.3 mm2.

A Low-Power, High-Fidelity Stereo Audio Codec in 0.13

A 1.5 V low-power stereo audio codec in 0.13 μm CMOS is described. The microphone path includes a programmable gain stage with an enhanced transconductance cell followed by a continuous-time ΣΔ ADC with capacitive feed-forward and capacitive direct feedback. The speaker path employs a 1 mA Class-AB speaker amplifier with an improved quiescent current control circuit that delivers 30 mW to a 32 Ω speaker. The audio input and output paths achieve 92 and 98 dB dynamic range, respectively, with 6.5 mA total quiescent current.

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A 60mW 111dB DR Class-G Stereo Headphone Driver is described. The driver utilizes higher-order loop filter to achieve PSRR of 120dB at the GSM TDMA rate of 217Hz. A driver architecture that combines Class-G and a split Class-AB/B amplifier reduces the quiescent current to 1.15mA/channel. A dual-voltage charge-pump with a single flying capacitor enables Class-G operation by adjusting the supply rails as a function of the input signal. The driver supports battery range of 2.65V–4.5V and occupies an area of 2.3mm2 in 0.18µm CMOS technology.

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A complete stereo ground-referenced headphone module that supports direct battery hookup is integrated on a 40 nm mobile baseband SoC. Several techniques were employed to guarantee the reliability of the module circuitry under high output swing and limited safe operating regions in this low-voltage technology. Additional techniques to reduce area and enable low-cost integration were also employed. The module delivers 3.24 Vpp to a 16Ω load (82 mW) and achieves 100 dB dynamic range (DR), 110 dB PSRR, and 84 dB THD+N with an area of 0.675 mm2 on the SoC.

A 60mW 1.15mA/channel Class-G Stereo Headphone Driver with 111dB DR and 120dB PSRR

Low-power and full-featured stereo audio CODECs are increasingly needed in wireless devices, such as Bluetooth headsets and smart phones. These portable devices are usually powered by low-voltage batteries with limited capacities. It is of particular importance that such CODECs be optimized for low-voltage operation and low-power consumption. The paper presents a 1.5V 10mW full-featured stereo audio CODEC that is integrated with a Bluetooth radio and PMU on a single die. As depicted in Fig. 4.5.1, the CODEC contains microphone PGAs, audio ΔΣ ADCs and DACs, speaker drivers and microphone bias generators.

A direct-battery hookup, fully integrated stereo headphone module with 82 mW output power and 110 dB PSRR

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.