Abstract: An apparatus and method is disclosed for achieving improved sound quality from mobile ‘hifi’ playback devices by driving compatible headphones in ‘balanced’ or ‘differential’ mode via standard size headphone connectors on the device, while retaining full compliance with legacy jack connections and conventional headphones. When a headphone is connected, a smartphone may determine whether the headphone is one capable of accepting balanced audio signals, or one that uses a conventional 3-pole jack or a 4-pole CTIA or OMTP jack. For a headphone that accepts balanced audio signals, the four poles of a 4-pole jack are used to drive left and right audio channels, and inverted left and right audio channels. For conventional 3-pole or 4-pole jacks, switches in the smartphone adapt the audio output signals to the configuration expected by the headphone.

Abstract: An apparatus and method is disclosed for achieving improved sound quality from mobile ‘hifi’ playback devices by driving compatible headphones in ‘balanced’ or ‘differential’ mode via standard size headphone connectors on the device, while retaining full compliance with legacy jack connections and conventional headphones. When a headphone is connected, a smartphone may determine whether the headphone is one capable of accepting balanced audio signals, or one that uses a conventional 3-pole jack or a 4-pole CTIA or OMTP jack. For a headphone that accepts balanced audio signals, the four poles of a 4-pole jack are used to drive left and right audio channels, and inverted left and right audio channels. For conventional 3-pole or 4-pole jacks, switches in the smartphone adapt the audio output signals to the configuration expected by the headphone.

Abstract: A discrete time sigma-delta modulator apparatus for class-D operation comprises a feed-forward path having an input at one end thereof and an output at another end thereof. A first summation unit is coupled in the feed-forward path to a first integrator. A quantizer is coupled in the feed-forward path after the first integrator and a feedback path arrangement is coupled to an input of the first summation unit. A low pass filter is arranged in the feedback path arrangement so as only to drive the first integrator.

Abstract: A discrete time sigma-delta modulator apparatus for class-D operation comprises a feed-forward path having an input at one end thereof and an output at another end thereof. A first summation unit is coupled in the feed-forward path to a first integrator. A quantizer is coupled in the feed-forward path after the first integrator and a feedback path arrangement is coupled to an input of the first summation unit. A low pass filter is arranged in the feedback path arrangement so as only to drive the first integrator.