Schmidt, Martin; Heck, Stefan; Dettmann, Ingo; Grözing, Markus; Berroth, Manfred (Institute of Electrical and Optical Communications Engineering, Universität Stuttgart, Stuttgart, Germany)
Wiegner, Dirk; Templ, Wolfgang (Alcatel-Lucent, Bell Labs Stuttgart, Stuttgart, Germany)
A continuous-time bandpass δ-σ modulator (CT BPDSM) for class-S power amplifier applications with a center frequency of 2.2 GHz is presented. Class-S amplifiers are considered to provide a very power efficient way to amplify signals with high dynamic range. The modulator has a multifeedback architecture. It features a low noise transconductor with series emitter degeneration, tunable LC resonators with Q-enhancement and an optimized clock tree operating at 7.5 GHz. The circuit is implemented in a 200 GHz-fT SiGe-bipolar technology. A peak SNDR of 43 dB in a bandwidth of 20 MHz is measured. The circuit dissipates 450 mW from a 3.6 V supply.