Abstract: A triggerable, pipelined 40-bit high speed accumulator includes trigger and continuous modes which can be operated at 50 MHz clock frequency. The high speed accumulator can be combined with static random access memory (SRAM) so as to be applied to digital frequency synthesizer, function generator and arbitrary waveform generator, etc. The high speed accumulator has two operation modes-trigger mode and continuous mode. Under trigger mode, the accumulator waits for a trigger signal to initiate its operation, while under continuous mode, the accumulator works without any trigger signal.

Abstract: A real time sensor for signal periods includes a zero crossing sensor for sensing a period of a signal and a noise evaluation circuit. If the noise of the signal is smaller than a predetermined value, the output of the zero crossing sensor is averaged over a plurality of zero crossings to obtain the signal period. The zero crossing sensor uses the average voltage level of the sampled signal preceding the currently sampled signal as an assumed DC bias level, which is subtracted from the sampled voltage values to determine the points at which the sampled signal crosses an axis in order to measure the period of the signal, and the noise evaluation circuit operates by comparing the peak-to-peak value of the currently sampled signal with a reference peak-to-peak value.

Abstract: A differential mode time to digital converter uses a pair of symmetric capacitors and a pair of constant currents to generate two charging curves with the same characteristics. By charging the capacitors at different timings to produce a voltage difference between the capacitors, and then holding and amplifying the voltage difference, a relationship between time and the digital signal is obtained, thereby reducing the effects of temperature on the electronic element and providing a high noise immunity, short conversion time, and high linearity.