| 摘要 |
In an audio amplifier, a DC offset compensation circuit is provided in which an offset compensating feedback path (107) comprises at least one voltage controlled oscillator (VCO) (108) and a counter (109). The VCO (108) provides, over time, a first VCO output signal based on the amplified output signal (Sout) and a second VCO output signal based on a reference signal (VREF). The counter (109) generates first pulse counts based upon the first VCO output signal and second pulse counts based upon the second VCO output signal and provides a compensation signal based on a comparison of the first and second pulse counts. The output signal of the counter (109) may be fed back via a DAC (112) or via digital paths (dotted). The low area occupied by the compensation circuit reduces the need to multiplex offset compensation across a large number of audio paths. In the present invention, the compensation circuitry is multiplexed between a first feedback loop for compensating offset in a first part of a signal path, and a second loop for compensating for offset in a second part of the signal path. |
