An analog-digital converter supplying a digital output signal in natural or reflected binary code, having an input stage, n consecutive conversion stages comprising two parallel channels of identical structure, in each of which there are two current paths in accordance with the result of a comparison of currents effected in the preceding stage and an output stage to which the switched currents proceed. In the complete converter there are 2.sup.n current paths corresponding to 2.sup.n quantization levels. Conversion is effected by means of a number of stages as small as the number n of bits of the desired digital signal. This converter is simple, fast, asynchronous, has a lower power consumption and its symmetry provides excellent automatic temperature compensation.
A folding-type A/D converter for converting an analog input signal to an n-bit digital code, the A/D converter having a transfer function dividing the analog input signal into at least n-1 segments, each such n-1 segment having an amplitude level corresponding to the significance of a given bit of the digital code and having linear parts which are mirror images of one another extending over 2.sup.n transition levels L. The A/D converter includes voltage-current converters for converting voltage input signals to current signals, a plurality of circuit stages for producing the linear parts in the current domain in response to the current signals, and a converter for converting the linear parts to a logic 1 or logic 0 of the bits of the digital code.
An analog-to-digital current converter comprises n series-connected stages which each provide one bit of the Gray code. For this purpose each stage m derives a difference current from the input current (i.sub.i/m), which is the output current (i.sub.0/m-1) of the preceding stage, and a reference current (I/2.sup.m-1) from a source (6). This difference current flows to the output (a) of the stage m (i.sub.o/m) either via a diode (3) or via a current (11) depending on its direction. Conduction of the diode (3) or of the current-mirror circuit (11) is used for the bit indication. This results in a very fast analog-to-digital converter with few components and a high accuracy and resolution.
A full-flash N-bit analog-to-digital converter with Gray-code digital output (V.sub.out) comprises only N current sources (CS.sub.1, CS.sub.2, CS.sub.3) to power the 2.sup.N -1 differential amplifiers connected to a voltage reference ladder RL and only N latches (L.sub.1, L.sub.2, L.sub.3) which directly furnish an N-bit Gray code at their outputs (LO). For this purpose the differential amplifiers are grouped and stacked in a particular manner and the output signals of the individual differential amplifiers in a group are cross-coupled to the inputs (LI.sub.1, LI.sub.2) of the latch associated with the group.
A continuous ADC for generating a digital representation, corresponding to a given quantized voltage level, of an analog input signal and for updating the digital representation at times when the approximate amplitude of the analog signal changes from one quantized level to another. A preferred embodiment includes a set of serially connected output stages with each stage for generating a bit output signal included in the digital representation and an analog residual output signal having an amplitude equal to a linear combination of the amplitude of the input analog signal and the prior bit output signals.
A high-speed bipolar logarithmic analog-to-digital (A/D) converter outputs signed binary number proportional to the logarithm of a bipolar analog input signal. A log converter is followed by a level shifting amplifier to center the output of the log converter on a temperature compensating reference. The reference voltage from the temperature compensating reference is used by a linear A/D converter to set the end points of the converter range. A code converter follows the A/D converter if a uniform absolute value coding is desired. Limiting the number of least significant bits (LSB) used to those representing the range of usable converter operation completes the device.
