Class D amplifier having PWM circuit with look-up table
AssigneeSynopsys, Inc.
InventorsDavid Filipe Correia Guilherme, Jorge Miguel Alves Silva Duarte
Life of this patent
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Abstract
A class D amplifier includes a noise-shaping modulator, a pulse width modulator, and a pulse amplifier. The noise-shaping modulator receive a pulse code modulated (PCM) signal and produces an oversampled PCM signal. The pulse width modulator produce a pulse width modulated (PWM) signal from the oversampled PCM signal. The pulse amplifier amplifies the PWM signal to produce an amplified PWM signal. The PWM uses a lookup table to convert from PCM to PWM. A compensation circuit optimizes amplifier performance. An optional demodulator filter converts the amplified PWM signal to an analog signal. The amplifier is ideal for integrated audio applications.
Claims20
An amplifier comprising:
- a noise-shaping modulator to receive a pulse code modulated (PCM) signal and to produce an oversampled PCM signal;
- a pulse width modulator to produce a pulse width modulated (PWM) signal from both the oversampled PCM signal and a lookup table referenced by the data in the PCM signal;
- and
- a pulse amplifier to amplify the PWM signal to produce an amplified PWM signal.
A class D audio amplifier comprising an amplifier power stage including MOSFETs arranged in an H-bridge configuration, wherein the gate width (Wopt) of each MOSFET is defined by:
- W
- opt
- =
- 3
-
- P
- o
- 2
-
- R
- L
-
- KC
- ox
-
- f
- sw
-
- V
- gs
- 2
-
- (
- V
- gs
- -
- V
- t
- )
- wherein Po is output power, RL is output load, fsw is switching frequency, Vgs is supply voltage, Vt is threshold voltage, K is a conduction factor, and Cox is gate-oxide capacitance.
A class D audio driver comprising:
- means for converting a pulse code modulated (PCM) signal to a pulse width modulated (PWM) signal using a lookup table referenced by the data in the PCM signal;
- and
- means for amplifying the PWM signal to produce an amplified signal.
Dependencies are inferred from the claim text.