An input signal Vin is sampled, when a first terminal of a sampling capacitor is connected to a node and a second terminal of the sampling capacitor is connected to an analog ground. A charge transfer operation is performed, when the first terminal of the sampling capacitor is connected to the analog ground and the second terminal of the sampling capacitor is connected to an inverting input terminal of an operational amplifier. A quantization is performed, when an output of the operational amplifier is input to a quantizer. Most significant bits are generated by repeating a subtraction operation in which a charge subtraction unit subtracts a charge accumulated in the integration capacitor based on a quantization result a predetermined number of times. Least significant bits are generated when a voltage provided by amplifying a voltage corresponding to a charge remaining in the integration capacitor is input to a sub-A/D converter after generation of the most significant bits. A sum of the most significant bits and the least significant bits are output as an output signal. Initialization of the charge of the integration capacitor, the charge transfer operation for a next A/D conversion, and generation of the most significant bits are performed in parallel with the A/D conversion in the sub-A/D converter after the generation of the most significant bits.

An image sensor pixel may include a photodiode, a floating diffusion, and a transfer gate. Column readout circuitry coupled to the image sensor pixel via a column line. The column readout circuitry may include sample and hold circuitry, comparison circuitry, residual measurement and summation circuitry, counter circuitry, analog-to-digital conversion circuitry, and digital summation circuitry. Column readout circuitry is configured to perform readout operations on a pixel image signal generated for a single frame in one or more portions, thereby extending the dynamic range of the imaging system without modifying pixel structure to generate high-dynamic range images within the single frame.

An analog-to-digital converter includes a cycle processing unit and a control unit. The cycle processing unit converts an analog input signal into a digital signal having a plurality of bits by performing a plurality of cycle processing on the analog input signal to acquire values of each bit in order from a higher-order bit to a lower-order bit. The control unit controls the cycle processing unit such that a period of the cycle processing is shortened according to a cycled number of the cycle processing.

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.

A circuit includes a first external terminal, a first lower resolution analog-to-digital converter (LRADC) coupled to the external terminal and configured to perform a first conversion of an analog signal received at the external terminal to a digital value, and a higher resolution analog-to-digital converter (HRADC). The HRADC is configured to selectively receive the analog signal from the first external terminal based on the digital value. When the digital value outputted by the first LRADC indicates a change in value of the received analog signal, the HRADC is provided with the analog signal and performs a second conversion of the analog signal to a second digital value. The first LRADC has a lower conversion resolution as compared to the HRADC.

An input signal Vin is sampled, when a first terminal of a sampling capacitor is connected to a node and a second terminal of the sampling capacitor is connected to an analog ground. A charge transfer operation is performed, when the first terminal of the sampling capacitor is connected to the analog ground and the second terminal of the sampling capacitor is connected to an inverting input terminal of an operational amplifier. A quantization is performed, when an output of the operational amplifier is input to a quantizer. Most significant bits are generated by repeating a subtraction operation in which a charge subtraction unit subtracts a charge accumulated in the integration capacitor based on a quantization result a predetermined number of times. Least significant bits are generated when a voltage provided by amplifying a voltage corresponding to a charge remaining in the integration capacitor is input to a sub-A/D converter after generation of the most significant bits. A sum of the most significant bits and the least significant bits are output as an output signal. Initialization of the charge of the integration capacitor, the charge transfer operation for a next A/D conversion, and generation of the most significant bits are performed in parallel with the A/D conversion in the sub-A/D converter after the generation of the most significant bits.

An A/D converter includes an A/D conversion circuit for converting an analog output signal into a digital signal, and a control circuit for controlling the A/D conversion circuit. The control circuit acquires a digital signal of a first bit indicating which level regions the voltage level of the analog output signal corresponds to in accordance with a first conversion operation by the A/D conversion circuit, sets a reference voltage corresponding to the level region based on the first bit, amplifies the difference voltage between the analog output signal and the reference voltage to correspond to the A/D conversion input range of the A/D conversion circuit, outputs an amplified analog signal, acquires a digital signal of a second bit indicating the voltage level of the amplified analog signal in accordance with a second conversion operation by the A/D conversion circuit, and synthesizes the first bit and the second bit.

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.

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.

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.