Patent ID: 7899415

Claim:
A radio system comprising: a power source; a power amplifier circuit coupled to the power source on a power line; and an active cancellation circuit, the active cancellation circuit coupled to the power source and said power amplifier circuit, the active cancellation circuit comprising: a bi-directional DC-DC converter; a high-frequency EMI filter, the high-frequency EMI filter coupled to said bi-directional DC-DC converter; a storage capacitor, the storage capacitor coupled with said bi-directional DC-DC converter, the bi-directional DC-DC converter is configured to sink and source current from the storage capacitor; a servo amplifier, the servo amplifier coupled to said storage capacitor and configured to control an average voltage across the storage capacitor; a pulse width modulator circuit, the pulse width modulator circuit is coupled to said bi-directional DC-DC converter and provides a control signal to said DC-DC converter to sink or source current from the storage capacitor; a compensation circuit, the compensation circuit provides an error signal to said pulse width modulator circuit, the pulse width modulator circuit translates said error signal to said control signal; and a differential amplifier communicatively coupled to the high-frequency EMI filter, the compensation circuit, and the power source, wherein the differential amplifier provides the error signal to the compensation circuit, wherein the differential amplifier creates the error signal by determining a difference between a resultant cancellation current provided by the high-frequency EMI filter and a current provided via the power amplifier circuit, the active cancellation circuit is configured to cancel low-frequency emissions from the power amplifier circuit on the power line based upon the error signal.