High-quality power ramping in a communications transmitter
View Patent ↗The present invention, generally speaking, provides for control of a modulator, such as a polar modulator or conventional linear modulator, to produce high quality RF signals that ramp quickly from a condition of minimal output power to a condition of information-bearing modulation at a specified output power and back down to the condition of minimal output power. Using a polar modulator, for example, it is theoretically possible to perform ramping without degrading the transient measurements beyond the degradation caused by the information-bearing modulation itself. This ideal can be closely approached in practice. Such ramping can be achieved without the need for extensive unit-by-unit calibration on the manufacturing line.
1. A ramping apparatus, comprising:
a GMSK signal generator operable to generate a GMSK signal;
a ramp generator operable to generate a ramp signal;
a non-linear power amplifier having a phase input port configured to receive the GMSK signal and an amplitude port configured to receive the ramp signal; and
a timing controller coupled to said ramp generator,
wherein the GMSK signal generator comprises:
a PAM modulator configured to receive digital bits; and
a frequency modulator having an input coupled to an output of the PAM modulator and an output operable to provide said GMSK signal, and
wherein the timing controller operable to provide timing signals to said PAM modulator and said ramp generator.
2. The ramping apparatus of claim 1 , wherein said ramp generator employs an EDGE pulse to generate the ramp signal.