Efficient implementation of an I-Q GMSK modulator

Automatic calibration of modulated frequency synthesizers

“…From Fig. 8, the transfer function between the ideal frequency modulation signal and the output phase error is found to be Assuming that we can further simplify (5) to produce (6) Substitution of (6) into (4) produces (7) We can rewrite (7) as (8) From (8) we see that an appropriate estimate for is (9) The prototype phase error waveform may be efficiently generated from the desired frequency modulation signal with a low-power digital filter. Fig.…”

“…This approach has enjoyed commercial success and several semiconductor manufacturers offer integrated circuits performing the quadrature modulation [5]- [7]. In addition to the commercially available integrated circuits which contain the two RF mixers, phase splitter, and combiner, there exist implementations of the baseband filtering, phase accumulation, lookup and the DACs on a single integrated circuit (IC) [8], [9].…”

A CMOS Fully Differential Σ-Δ A Frequency Synthesizer for 2-Mb/s GMSK Modulation

“…VCO (2) Substituting resistor R2, capacitor Cl and C2 into H(f) with, we get: From this formula, we can see that the close-loop transfer function is sensitive to lop, KVCO, C,, C2 and R2.…”

“…There are basically three methods to realize the GMSK modulator. First is the Cartesian architecture [2] - [5]. The Cartesian architecture is in fact a quadrature up-conversion structure.…”

“…In recently several years, the study of the GMSK modulator is very active [2] [ {13]. There are basically three methods to realize the GMSK modulator.…”