Fastest CMOS output comparators feature rise and fall times of just 1.2ns

With fast rise and fall times of 1.2ns and a toggle frequency of 280MHz, Linear Technology's new LTC6752 family of comparators are the fastest CMOS output comparators available, says the company. Designed for driving logic levels from 3.3V down to 1.8V, the LTC6752 exhibits only 2.9ns of propagation delay and overdrive dispersion of only 1.8ns. Jitter is only 4.5ps for a 100mVpp, 100MHz sinusoidal input, and the outputs swing to within 200mV of the rails with up to 8mA of load current. All of this high speed performance is well suited for a broad range of timing-critical applications, where fast response times and CMOS output levels are required. The LTC6752 consists of 5 options offered in different packages with unique combinations of features, such as separate input and output supplies, low power shutdown, output latch, adjustable hysteresis and complementary outputs. The latch provides the ability to quickly capture the state of the comparator. With the adjustable hysteresis feature, the default 5mV hysteresis can be increased up to 40mV for clean switching in the presence of noisy input signals, and it allows for hysteresis to be completely eliminated. The separate input and output supply allows the output logic level to be independent of the input signal range for translation from one logic level to another. With the shutdown, power can be reduced while enabling the comparator to wake up quickly. In addition, the complementary CMOS outputs simplify logic interfaces and eliminate the need for separate logic inversion. The inputs for the LTC6752 extend beyond both rails, particularly useful for single supply operation. All members of the LTC6752 family are capable of driving 3.3V and 2.5V logic. The LTC6752-2, LTC6752-3 and LTC6752-4 have separate input and output supplies, decoupling the input and output voltage levels and enabling them to drive 1.8V logic, says the company. "The LTC6752 family greatly expands the capabilities of CMOS output comparators with unprecedented speed and performance" stated Brian Hamilton, design manager, Linear Technology. "Each option combines a unique set of features to address a wide range of applications." The LTC6752 family is offered in the TSOT23, SC70, MSOP8 and a 12-lead 3mm x 3mm QFN package. These parts are fully specified over two temperature ranges: -40C to 85C and -40C to 125C.