ICs or circuits for generating 80-90 MHz square wave signals

The discussion addresses generating a 0-5V, 50% duty cycle square wave signal at 80-90 MHz with a resistive load. High-speed integrated circuits such as emitter-coupled logic (ECL) D-type flip-flops (e.g., ON Semiconductor MC10EL52 and MC100EL52) can generate square waves up to 1800 MHz by clocking at twice the desired frequency and feeding the D input from the inverted Q output. ECL voltage-controlled oscillators like the 1648 model can also be used, though their output swing is less than a volt and may require amplification and offset adjustment using high slew rate amplifiers. Alternatives include high-speed TTL logic families, monolithic buffer/drivers, and fast comparators to convert sine waves to square waves with adjustable duty cycles. For frequency stability or continuous tuning across 80-90 MHz, phase-locked loops (PLL) or direct digital synthesis (DDS) chips are recommended, typically requiring a processor for control. Op amps capable of operating at these frequencies exist but are sensitive to capacitive loading and require high-impedance loads for optimal performance.
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