The HMC660LC4B is a SiGe monolithic, fullydifferential, track-and-hold that provides unprecedented bandwidth and performance to wideband sampled signal systems. The novel design and low aperture jitter enable 9 to 10-bit signal capture from 20 MHz to 4.5 GHz while sampling to 3 GS/s. The narrow sampling aperture allows signal acquisition at frequencies well beyond the input bandwidth. The output can be held for 5 ns, enabling lower-speed ADCs to sub sample a high frequency wideband input signal.