A Software-Aided Time Resolution Doubler (TRD) Operating as a TDC

A Ratio-to-Digital Converter (RDC) is used to determine the position of ionization in a single wire position sensitive proportional counter. In the RDC, the digital output is obtained by a TDC utilizing the principle of a linear discharge type ADC. The conversion time as well as the time resolution of this type of ADC is dependent on the frequency of the clock. An idea of a Time Resolution Doubler (TRD) has been conceived by applying a simple logic to the basic idea of a two-phase active TDC system to double the effective operating frequency of a TDC. The final output is obtained by the help of the data processing software. An attempt is made to minimize the problem of differential nonlinearity, a factor that limits the practical use of a two-phase active TDC system. A prototype TRD has been developed for using as a TDC in the RDC system of this laboratory. Utilizing a 100 MHz clock, the TRD acts as an effective 200 MHz TDC and gives the RDC output with a full scale capacity of 8192 channels. The experimentally observed differential nonlinearity of the TRD based RDC is comparable to that of a conventional TDC based RDC.