A MMIC compatible photonic A/D converter

Wideband surveillance system and sensor performance is limited by the spurious free dynamic range of mixer and analogue-to-digital converter (ADC) technologies. To improve the performance of RF surveillance systems, a direct conversion receiver approach can be taken where the mixer and ADC combination is replaced by a bandpass ADC, and the performance is then limited by the ADC specification. This paper proposes an ADC for this application which uses Sigma-Delta (/spl Sigma/-/spl delta/) lowpass and bandpass modulator structures implemented with an ultra low timing jitter (ULTJ) oversampling clock and novel opto-electronic components. The photonic devices can be monolithically integrated on the same substrate as MMIC amplifiers.