Voltage-to-current architecture and error correction schemes

#The present disclosure relates to audio signal processing, and more specifically, to circuitry for voltage-to-current conversion.

#A speaker is a transducer that produces a pressure wave in response to an input electrical signal, and thus, sound is generated. The speaker input signal may be produced by an audio amplifier that receives a relatively lower voltage analog audio signal and generates an amplified signal (with a relatively higher voltage) to drive the speaker. A dynamic loudspeaker is typically composed of a lightweight diaphragm (a cone) connected to a rigid basket (a frame) via a flexible suspension (often referred to as a spider) that constrains a voice coil to move axially through a cylindrical magnetic gap. When the input electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the coil, thereby forming a linear electric motor. By varying the electrical signal from the audio amplifier, the mechanical force generated by the interaction between the magnet and the voice coil is modulated and causes the cone to move back and forth, thereby creating the pressure waves interpreted as sound.

#Certain aspects of the present disclosure are generally directed to circuitry and techniques for current sensing, such as sensing current to a speaker in an audio application.

#FIG. 1 illustrates an example audio amplifier system, in accordance with certain aspects of the present disclosure.

#FIG. 2 illustrates a circuit for voltage-to-current conversion, in accordance with certain aspects of the present disclosure.

#FIG. 3 illustrates a circuit for voltage-to-current conversion implemented with resistor calibration networks and capacitive calibration networks, in accordance with certain aspects of the present disclosure.

#Certain aspects of the present disclosure are generally directed to circuitry and techniques for current sensing. For example, drive current for a speaker may be sensed for temperature control. Certain aspects provide voltage-to-current circuitry and error correction circuitry for the current sensing, as described in more detail herein.

#FIG. 1 illustrates an example audio amplifier system 100 (also referred to as an “audio system”), in accordance with certain aspects of the present disclosure. As illustrated, a digital signal processor (DSP) 102 may receive and process audio signals 114 (e.g., a digital audio signal) by applying a digital filter aimed at increasing audio quality. The filtered digital signal 120 produced by the DSP (or a further processed version thereof) may be used to control an amplifier 110 to generate an amplified signal 122. The amplified signal 122 may drive a speaker 112 to produce an acoustic output (e.g., sound waves) 124.

#High output volume in mobile devices is becoming more and more important in next-generation mobile devices. Higher volume directly translates to higher output power. The higher volumes may be difficult to achieve with the relatively low voltages provided by lithium-ion batteries. Therefore, on-chip boost switchers may be used to boost the battery voltage to a higher level that supplies the speaker power amplifier (e.g., amplifier 110). The amplifier 110 may be implemented as a class-D amplifier due to the relatively high power efficiency associated with class-D amplifiers compared to other amplifier classes. The efficiency of the class-D amplifier may be further improved by implementing the class-D amplifier in an H-bridge configuration, as described below with respect to FIG. 2.