A 2.5MHz 55dB switched-current bandpass ΣΔ modulator for AM signal conversion

We present a Switched-Current (SI) fourth-order bandpass ΣΔ modulator IC prototype. It uses fully-differential circuits in 0.8µm CMOS technology to obtain a Dynamic Range (DR) larger than 55dB at 2.5MHz center frequency with 30kHz bandwidth - in accordance to the requirements of AM digital receivers. The prototype incorporates a single-ended to fully-differential current-mode buffer for testing purposes. The power consumption of the whole prototype (modulator plus buffer) is 60mW from a 5V supply voltage.

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