| 摘要 |
<p>An unknown analog signal is compared in amplitude with the signal from a digital-to-analog (D-A) converter. The converter, preferably monotonic, may be at least partially formed from a plurality of switches connected in a matrix relationship to define sub-sets having a recurrent relationship. An adjustable-gain amplifier produces a difference signal having an amplitude indicating the amplitude comparison. A flash converter converts the difference signal to binary signals. These binary signals are modified and fed back to the D-A converter to obtain from this converter an output signal having an amplitude approximating the amplitude of the unknown analog signal. A plurality of successive approximations of the analog signal may be provided in this manner. In at least one (1) of these approximations, the gain of the amplifier may be increased to increase the sensitivity of the approximation by increasing the gain of the difference signal. In such approximation(s), before the binary signals from the flash converter are fed back to the D-A converter, they are shifted downward in binary significance by a factor related to the increase in the amplifier gain. The flash converter may be formed from a plurality of comparators, each constructed and connected to indicate whether the amplifier signal has an amplitude within an individual voltage increment. One of these comparators may be more precise than the others to more accurately indicate the sign of the amplitude difference between the unknown analog signal and the digital-to-analog signal in some approximations, particularly the final approximations.</p> |
