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This article presents a quasi-load insensitive (QLI) Doherty power amplifier (DPA). The proposed theory makes the amplifier load insensitive in terms of output power, while its efficiency is slightly degraded for complex loads. The load insensitiveness is achieved by dynamically changing the supply voltages ( ${V_{DD}}$ ) and the input power splitting for both the carrier and peaking transistors. The optimal, load-dependent, ${V_{DD}}$ values are theoretically derived from back-off (BO) and full power conditions using load line theory. The optimal input excitation signals for the carrier and peaking devices are also derived for these variable ${V_{DD}}$ conditions. A 3.6-GHz QLI DPA was designed, and a complete system, composed of the DPA output stage, a two-channel medium power driver, an adaptive input driving stage, and a load sensing system, was implemented. The laboratory measurements have been performed for loads distributed inside a 2.0 maximum voltage standing wave ratio (VSWR) circle and show an output power variation between 43.8 and 42.6 dBm and a BO efficiency between 50% and 35%. Under modulated signal excitation, for the worst case loads, the peak output power capability of the DPA is improved from 41.7 to 43.1 dBm, and the average efficiency is increased from 32.6% to 43%.

Introduction Statin therapy is associated with an increased risk of developing diabetes. Among bariatric patients, the influence of this therapy on various metabolic outcomes, such as diabetes status and its remission, is largely unknown. Methods This was a retrospective study of 1710 patients who underwent bariatric surgery at our hospital between January/2010 and June/2017. We compared patients with and without statin therapy at baseline, 12 and 24 months after surgery regarding statin use and its impact on several clinical and analytical parameters. Multiple linear regression was performed, adjusting differences for age, sex, surgery type, antidiabetic drugs at baseline, hypertension at baseline, LDL cholesterol ˃ 130 mg/dL, weight variation one year after surgery, and age of obesity onset. Results The overall prevalence of statin use was 20.2% before, 13.6% 12 months after surgery, and 15.0% 24 months after surgery. There was a larger reduction in fasting glucose and HbA1c at 12 and 24 months after surgery among statin-treated patients, with the opposite trend for weight reduction and BMI. Statin-treated patients with diabetes had lower diabetes remission rates (45.3 vs 68.5%) 12 months after surgery, with the highest reduction in HbA1c (1.3±1.3 vs −1.1±1.2%; p=0.042), fasting glucose (−40.8±48.8 vs −30.9±41.6 mg/dL; p=0.028), and insulin (−21.7±28.2 vs −13.4±14.2 mIU/L; p=0.039). The proportion of new-onset cases of diabetes was equal between statin-treated vs non-treated individuals at 12 months (1.9%) and 24 months (1.0%) after surgery. Conclusion Bariatric surgery seems to lead to diabetes remission more frequently in patients not treated with statins. A larger reduction was observed in fasting glucose and HbA1c among statin-treated patients. Statin did not contribute to an increased proportion of new-onset diabetes after surgery.