An 18 GHz continuous time /spl Sigma/-/spl Delta/ modulator implemented in InP transferred substrate HBT technology

We report an 18 GHz clock-rate, 2/sup nd/ order continuous-time /spl Sigma/-/spl Delta/ modulator implemented using InP transferred substrate HBTs. Under two-tone test conditions, the modulator achieved 43 dB and 33 dB SNR at signal frequencies of 500 MHz and 990 MHz, respectively. The latter is equivalent in performance to a 1.98 GS/s Nyquist-rate ADC with 6.2 bits resolution. The IC occupied 1.95 mm/sup 2/ die area and dissipated /spl sim/1.5 W.