| 摘要 |
A voltage-selecting tracking power supply with an asynchronous delta-sigma controller A coarse output 16 for an envelope tracking power supply is provided by selecting one of a set of voltages V1-V4 in dependence on the output of a sigma-delta controller comprising a feedback subtractor 18, loop filter integrator 20, and multiple-output quantiser 6. Positive feedback around the quantisers 26, in conjunction with a ramp output from the loop filter 20, provides self-oscillation. Output potentials between the voltages V1-V4 may be obtained by coupling the outputs of two voltage selectors 34 through inductors (figure 6). The outputs of the selectors may be transposed periodically to prevent excessive imbalance in the currents provided by the two selected voltage rails. A balancing block (figure 7) may operate to select voltage outputs which reduce current imbalance when the detected imbalance is excessive. |
