HYPERLABS has developed a DC to 20 GHz harmonic down-converter/sampler IC targeted for use in SIGINT and spectrum monitoring applications. The HL9333 delivers excellent linearity, low noise and high LO to RF isolation in a 28-pin 4 mm QFN package. This product is specifically designed for Nyquist folding receiver applications. It extends the analog bandwidth of high speed A/D converters, simplifying the design of network analyzers, spectrum analyzers and sampling oscilloscopes. The RF front-end features 50 Ω terminations to ground and a buffer amplifier. The combined 3 dB bandwidth of the RF amplifier and mixer is typically DC to 17 GHz. The LO to RF isolation is 75 dB.
The LO comb generator produces a broad spectrum of harmonics. Each LO harmonic converts two Nyquist zones from RF to IF baseband. When sampling at the recommended 1 GSPS, 40 Nyquist zones of the DC to 20 GHz RF spectrum are folded and aliased into the IF baseband. Signals from the even Nyquist zones are spectrally inverted. The buffered IF output features 50 Ω terminations to VDD (+6 V). The IF bandwidth is 700 MHz.
The HL9333 can operate at LO frequencies as high as 7 GHz with little effect on RF bandwidth. For broadband applications, the maximum recommended LO is 1.4 GHz. The IF mixing products at 700 MHz are attenuated by 3 dB relative to the lower frequency mixing products due to IF bandwidth limitations. This results in a 3 dB ripple when operated at 1.4 GSPS. For narrowband applications, a higher LO frequency may be selected if the channels of interest fall within the 700 MHz IF range.