Continuous-Time Bandpass Delta-Sigma Modulator for a Signal Frequency of 2.2 GHz
01 January 2009
A continuous-time bandpass delta-sigma 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 multi-feedback 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.