Variable feedback architecture and control techniques for variable gain amplifiers concurrently maintain, across a wide range of VGA gain settings, minimal input and output impedance variations, a low noise figure, low rates of change in noise figure, high signal-to-noise ratio, high quality of service, low distortion, high and relatively constant output third order intercept point. Preferred compositions additionally comprise inhibitors of DP IV or DP IV-like enzymes for the treatment or alleviation of conditions that can be treated by modulation of QC- and DP IV-activity. A third section stores information about setting of operation of an external device. The expansion coefficients in the axial sense of the spring and of the balance wheel are of opposite sign and they compensate one another.