In recent years, there has been considerable interest in highly
integrated, low power, portable wireless devices. There are three
primary areas to be addressed when higher performance and lower power is
desired. The first area is the device technology. Scaling of devices has
realized steady improvements for many years. The second area is improved
circuit design techniques. The final area is at the architectural level.
This monograph focuses on the problem of low power GFSK/GMSK modulation
and presents an architectural approach for improved performance. The new
architecture is a modulated S-D fractional-N frequency synthesizer. The
key innovation is an automatic calibration technique, which operates in
the background. The availability of the calibration circuit makes high
data rate, low power modulation possible.
From the Foreword: "The key contribution of the work presented in
this monograph is a technique for in service automatic calibration of
the modulated frequency synthesizer by ensuring that the digital
emphasis filter and analog loop filter characteristics are matched. The
automatic calibration circuit operates while the transmitter is in
service and compensates for process and temperature variation. GFSK and
4-GFSK modulation was demonstrated at data rates of 2.5 Mb/s and 5 Mb/s
respectively at an RF output carrier frequency of 1.8 GHz. ... In
addition, he presents some valuable tools for the practicing engineer in
this field." by Charles G. Sodini