Title :
A combined LC/gmC 4th order continuous-time bandpass Σ Δ modulator
Author :
van Engelen, J. ; van de Plassche, R.
Author_Institution :
Eindhoven University of Technology, Eindhoven, Netherland
Abstract :
A fourth order bandpass ΣΔ modulator has been designed using a continuous-time loopfilter. The loopfilter was implemented using an LC resonator combined with a transconductor-capacitor (gmC) resonator. This structure allows the use of a high-Q LC resonator but ensures enough degrees of freedom to design the desired discrete-time loopfilter. A test circuit tuned at 10.7 MHz and sampled at 40 MHz was build using discrete components for the loopfilter. The measured SNR is 54.4 dB for a 200kHz bandwidth, 61 dB for 9 kHz bandwidth, and an IM3 < -76 dB for a Δf = 9kHz.
Keywords :
Band pass filters; Circuit testing; Filtering theory; Frequency; Phase modulation; Poles and zeros; Pulse modulation; Quantization; Transfer functions; Tuning;
Conference_Titel :
Solid-State Circuits Conference, 1998. ESSCIRC '98. Proceedings of the 24th European
Conference_Location :
The Hague, The Netherlands
DOI :
10.1109/ESSCIR.1998.186232
