Serial radio frequency to baseband interface with power control

1. An RF front end for a satellite positioning system receiver, the front end comprising:

an RF processing section comprising an RF input for receiving satellite positioning system signals;

an RF to baseband interface coupled to the RF processing section, the interface comprising:

a bi-directional message interface for communicating messages between the RF processing section and a baseband processing section, including receiving a power control message from the baseband processing section wherein the power control message is associated with power consumption of the RF processing section, wherein the RF section includes a register for receiving the power control message from the baseband section and wherein devices to be controlled by the power control message are coupled to the register to receive respective power control data from the received power control message;

a data interface for communicating data from the RF processing section to the baseband processing section;

wherein the message interface comprises:

a message clock line;

a message-in signal line and

a message-out signal line; and

wherein the message-out signal line carries an output bit stream representing the power control message, the data interface comprises a data clock signal line and a data bit signal line; and

the data clock signal line carries a data clock comprising a rising edge and a falling edge;

the data bit signal line carries a data signal comprising a sign bit and a magnitude bit; and

the first data bit is valid on the rising edge of the data clock and the second data bit is valid on the falling edge of the data clock.