Multiple-bit parallel successive approximation (SA) Flash analog-to-digital converter (ADC) circuits are disclosed. In one aspect, a multiple-bit parallel SA Flash ADC circuit includes a digital-to-analog converter (DAC) circuit that receives reference voltage and trial bit codes, and generates DAC analog signals. The SA Flash ADC circuit includes parallel comparator stages, each including one or more comparator circuits equal to two (2) raised to a number of digital bits of the corresponding parallel comparator stage, quantity minus one (1). Each comparator circuit receives an analog input signal and corresponding DAC analog signal, and generates a digital signal. The digital signal of each comparator circuit is logic high if the analog input signal has a greater voltage than the corresponding DAC analog signal, and logic low if the analog input signal has a smaller voltage. The digital signals corresponding to each parallel comparator stage are used to generate a digital output signal.

An A/D converter 1 includes a front stage A/D conversion unit (3) including a first A/D conversion unit (6) that receives an analog signal from a CMOS image sensor (100) and generates a first digital value (D1) and a first residual analog signal (V.sub.OPF) through a folding integration A/D conversion operation, and a second A/D conversion unit (7) that receives a first residual analog signal (V.sub.OPF) from the first A/D conversion unit (6) and generates a second digital value (D2) and a second residual analog signal (V.sub.OPC) through a cyclic A/D conversion operation, and a rear stage A/D conversion unit (4) that receives the second residual analog signal (V.sub.OPC) from the front stage A/D conversion unit (3) and generates a third digital value (D3) through an acyclic A/D conversion operation.

An analog to digital converter comprising: a plurality of voltage generators, each voltage generator having a control input and being capable of generating an output whose voltage is dependent on a signal applied to the control input; a comparison stage arranged to compare the input signal with one or more outputs of the voltage generators and generate one or more comparator outputs indicative of the result(s) of the comparison(s); and a controller arranged to receive the comparator outputs, the controller being configured to: (i) signal the control inputs of a number V.sub.1 of the voltage generators, and estimate a number B.sub.1 of bits of the digital representation; and subsequently (ii) signal the control input(s) of a number V.sub.2 of the voltage generators, and estimate a number B.sub.2 of bits of the digital representation; wherein V.sub.2 is less than V.sub.1.

The present technology relates to a conversion apparatus, an imaging apparatus, an electronic apparatus, and a conversion method that are capable of reducing the scale of a circuit. The conversion apparatus includes: a comparison unit that compares an input voltage of an input signal and a ramp voltage of a ramp signal that varies with time; and a storage unit that holds a code value when a comparison result from the comparison unit is inverted, the holding of the code value by the storage unit being repeated a plurality of times, to generate a digital signal having a predetermined bit number. The predetermined bit number is divided into high-order bits and low-order bits, the low-order bits are acquired earlier than the high-order bits, and the acquired low-order bits and the high-order bits are combined with each other, to generate the digital signal having the predetermined bit number. The present technology can be applied to a portion of an image sensor, in which AD conversion is performed.

A successive approximation type A/D conversion circuit includes a first capacitor circuit, a second capacitor circuit, a plurality of comparison circuits, a determination circuit, and a control circuit. The determination circuit counts a first number of first state and a second number of second state with respect to a plurality of first digital signals output from the plurality of comparison circuits. The determination circuit outputs a control signal for stopping the plurality of comparison circuits to the control circuit when an absolute value of a difference between the first number and the second number is equal to or smaller than 1. The control circuit stops the plurality of comparison circuits on the basis of the control signal.

A digital correlated double sampling (CDS) circuit includes a first latch circuit, a first converting circuit, a second converting circuit, a second latch circuit, and a calculating circuit. The first latch circuit latches an input phase shift code based on a first control signal to store first and second phase shift codes. The first converting circuit converts the first and second phase shift codes into first and second Gray codes. The second converting circuit converts the first Gray code and the second Gray code into a first binary code and a second binary code. The second latch circuit latches an output of the second converting circuit based on a second control signal to store the first binary code. The calculating circuit operates on the first binary code and the second binary code to generate a third binary code, and outputs the third binary code.

An A/D converter includes: an integrator circuit executing modulation to an analog signal to be converted; an adder outputting an addition result of at least an output signal of the integrator circuit and a first reference signal as a reference signal of modulation; a quantizer receives an output signal of the integrator circuit, an output signal of the adder, and a second reference signal as a reference signal in cyclic A/D conversion to generate a result of quantization of the output signal of the integrator circuit and the output signal of the adder; and a controller is configured to switch between a modulation mode and a cyclic mode.

A cyclic analog to digital converter for digitizing an output from a photoplethysmography sensor has a buffer amplifier for setting a voltage of the feedback capacitance. Additionally, digital averaging circuit is preferably provided for averaging the digital output from the cyclic analog to digital converter for the several conversions. Finally, voting logic is additionally provided for declaring the digital bits based on successive comparisons by the one or more comparators.

A SAR ADC includes a first capacitor array, a first comparator, a second capacitor array, a second comparator, an arbiter and a control circuit. The first capacitor array is arranged for receiving an input signal to generate a first signal. The first comparator is arranged for comparing the first signal with a first reference signal to generate a first comparison result. The second capacitor array is arranged for receiving the input signal to generate a second signal. The second comparator is arranged for comparing the second signal with a second reference signal to generate a second comparison result. The arbiter is arranged for generating an arbitration result according to the first comparison result and the second comparison result. The control circuit is arranged for generating an output signal according to the first comparison result, the second comparison result and the arbitration result.

Provided is an ADC in which a plurality of pixel signals input through a vertical signal line of a solid-state image pickup apparatus are held in advance using some capacitors among a plurality of capacitors within the ADC. A potential of a node is generated by the respective pixel signals held in the capacitors. Thereafter, the potential of the node is changed by changing the voltages of counter electrodes of the capacitors, and the digital values of the pixel signals are generated by comparing the potential of the node with a predetermined potential.