| 摘要 |
1,211,111. Analogue to digital converters. TELEFONAKTIEBOLAGET L. M. ERICSSON. 25 Jan., 1968 [26 Jan., 1967], No. 4047/68. Heading G4H. A stage of an analogue-to-digital converter of the stage-by-stage type comprises a first amplifier Fl, Fig. 2, receiving the input Is of the stage and which has a constant negative amplification within a certain part of the amplitude range and outside this part gives a constant output a (Fig. 3a), an adding circuit A for adding this output to the input signal to produce a signal b (Fig. 3b) giving a V-shaped transfer characteristic, and a second amplifier F2 with negative amplification to produce an output (Fig. 3c) which is applied to the next stage and to a threshold detection circuit. In the form of Fig. 3 the first amplifier F1 has an amplification of - 2 within the middle third part of the range and the second amplifier has an amplification of - 3. The threshold detectors have three signal levels and each produce one out of three different signals depending on which level has been exceeded. The amplifier F1 comprises an amplifier F, Fig. 4, with amplification factor of - 2, having an input via capacitor Cl and an output via capacitor C2. Diodes R1 and R2 are connected to bias levels Π2U/3 and limit the output values to these levels. In another form the second amplifier F2, Fig. 2, has a gain of - 2 and the detectors have only two levels of discrimination. The output is then in binary Gray code. |
