| 摘要 |
The outputs of each stage of a quadrature oscillator are matched in amplitude by an automatic amplitude control circuit which controls the amplitude of each oscillator stage. The automatic amplitude control circuit may comprise dual control circuits, one for each stage, or a singular control circuit which generates control signals for both stages. The output signals from each of the stages are used by the automatic control circuit in conjunction with a common amplitude control reference to generate the amplitude control signal for that stage. The stages may be voltage controlled oscillators (VCOs) which may be coupled by inverted feedback, for example they may be cascaded cross-coupled oscillators. The object of the amplitude matching is to reduce sensitivity to device mismatch effects. The quadrature oscillator circuit may be incorporated in an ultra-wideband communication system. |
