Simulation of Transient Processes in the Fast Track-and-Hold Circuits

Abstract

The dynamic errors of the track-and-hold circuit (THC) in the signal track mode for the sinusoidal signal were analyzed. The output signal time diagrams, which depend on the parasitic electrical parameters of the internal and external circuit, were presented. The results of the modeling, when the THC is intended for the 8 and 10-bit ADC with two different sets of the parasitic electrical parameters of the THC, were presented. It has been determined that the best hold time constant is 120-500 fs for the THC clock speed of 5 GHz. In such a case, the precision of the THC is about 0.5 of the least significant bit (LSB) for the 8-bit ADC and about 0.75 LSB for the 10-bit ADC. When the values of the parasitic inductances increased from 0.05 nH to 0.2 nH, the THC precision decreased slightly. When the linear part length of the amplifier transfer characteristic is 0.05 V, in order to obtain the analog signal frequency of 1 GHz with the 50 dB SNR, the equivalent holding time constant of 200 fs needs to be chosen. The results of the research allow us to choose more optimally the THC characteristics depending on the needed signal processing frequency and the THC precision. Ill. 6, bibl. 7 (In English; summaries in English, Russian and Lithuanian).