single slope adc

A low-power column-parallel gain-adaptive single-slope analog-to-digital converter (ADC) for CMOS image sensors is proposed. Want to see this answer and more? A plurality of ramp signals are generated which define non-overlapping sub-ranges of the full input range. See Answer. © 2020 Springer Nature Switzerland AG. The column-parallel single-slope ADC (SS-ADC) architecture is widely adopted for CIS because of its simplicity, low power consumption, and high linearity. Want to see the step-by-step answer? The spring is then turned, or “wound up,” by the rotating shaft (input signal) for a fixed amount of time. The basic schematic diagram is shown here: The IGFET capacitor-discharging transistor scheme shown here is a bit oversimplified. pp 93-97 | Since the single-slope analog-to-digital converter with correlated double sampling (CDS/SS-ADC) in a CMOS image sensor (CIS) is composed of several operation phases in which the circuit topologies are different from each other, the noise cannot be estimated by the conventional FNS. A single-slope ADC, particularly suitable for use in a massive-parallel ADC architecture in a readout circuit of a CMOS imager. Any changes in the analog signal during that period of time have a cumulative effect on the digital output at the end of that cycle. Therefore, to guarantee measurement accuracy, the reference voltage used as one of input of the comparator must be accurate and stable. The accurate correspondence of this ADC\’s output with its input is dependent on the voltage slope of the integrator being matched to the counting rate of the counter (the clock frequency). The time it takes for the integrator to trip the comparator is proportional to the unknown voltage (T INT /V IN). Operation: The example shown is an N-bit ADC. For each ADC channel, the sub-range in which the voltage of the input signal falls is determined, and the corresponding ramp signal is selected … It utilizes a statistical approach and code-prediction methods to improve the conversion speed of standard single-slope ramp (SSR) ADC. A multi-slope run-down can speed the measurement up without sacrificing accuracy. Based Single Slope ADC For CMOS Image Sensor Column Readout @inproceedings{Guo2011BasedSS, title={Based Single Slope ADC For CMOS Image Sensor Column Readout}, author={Jia Guo}, year={2011} } Jia Guo; Published 2011; ACKNOWLEDGMENTS Since I left my country to study abroad, two years almost passed. Advantages: It is more accurate ADC type among all. Both ADCs make use of simple op-amp circuits and control logic to do most of their work. The sampling rate is determined by the user’s configuration of the clock sources and is limited to a maximum of 8.8 ksps. Single-slope ADC is the simplest form of an integrating ADC. An ADC is represented by the schematic symbol in figure 1. Series-Parallel Resistor Circuit Analysis, Building Series-Parallel Resistor Circuits, Resonant circuit Bandwidth and Quality Factor, Introduction to Mixed-Frequency AC Signals, Power in Resistive and Reactive AC Circuits, Introduction to Solid-state Device Theory, Insulated Gate Field Effect Transistors (MOSFET), Introduction to Bipolar Junction Transistors, Introduction to Junction Field-effect Transistors (JFET), Junction Field-effect Transistor as a switch. In the case of FIG. In dual slope type ADC, the integrator generates two different ramps, one with the known analog input voltage VA and another with a known reference voltage –Vref. The first comparator outputs a compared signal by receiving and comparing an input signal having a constant level with a ramp signal, the second comparator has a hysteresis property having an input terminal connected to an output terminal of the first … The accurate correspondence of this ADC’s output with its input is dependent on the voltage slope of the integrator being matched to the counting rate of the counter (the clock frequency). Part of Springer Nature. Single-Slope ADC Architecture The simplest form of an integrating ADC uses a single-slope architecture (Figures 1a and 1b). With the digital ramp ADC, the clock frequency had no effect on conversion accuracy, only on update time. Noise analysis of the ramp reference voltage and its projection at the output of a conventional single-slope ramp analog-to-digital converter (ADC) is presented. ADC Converters – Track & hold (continued) • T/H aperture uncertainty – ADC architectures and design • Serial- slope type • Successive approximation • Flash ADC and its sources of error: comparator offset, sparkle code & meta-stability – Comparator design • Single-stage open-loop amplifier • Cascade of open-loop amplifiers 즉, 공정 variation에 매우 취약하다. An alternative A/D conversion technique uses the single-slope A/D converter. The measurement cycle begins with the spring in a relaxed state. The time it takes for the integrator to trip the comparator is proportional to the unknown voltage (TINT/VIN). This technique of analog-to-digital conversion escapes the calibration drift problem of the single-slope ADC because both the integrator\’s integration coefficient (or “gain”) and the counter\’s rate of speed are in effect during the entire “winding” and “unwinding” cycle portions. This paper gives insight on the reference voltage noise origins during the continuous-time ramping phase of column-parallel CMOS image sensor ADCs, as well as its effect on the final ADC output noise. It is shown that SSLAR ADC reduces power consumption while achieving an increased frame rate. The only good thing to say about this circuit is that it avoids the use of a DAC, which reduces circuit complexity. We'll assume you're ok with this, but you can opt-out if you wish. Single Slope 8-Bit ADC Document Number: 001-13249 Rev. Octal and Hexadecimal to Decimal Conversion, Switch Contact Normal State and Make/Break Sequence, Converting Truth Tables into Boolean Expressions, Making a Venn Diagram Look Like a Karnaugh Map, Karnaugh Maps, Truth Tables, and Boolean Expressions, Introduction to Combinational Logic Functions, Parallel-in Serial-out Shift Register (PISO), Serial-in Parallel-out Shift Register (SIPO), Serial-in Serial-out Shift Register (SISO), Binary Weighted Digital to Analog Converter, Introduction to Digital to Analog Conversion, Practical Considerations of Digital Communication, Introduction to Microprocessor Programming. In reality, a latching circuit timed with the clock signal would most likely have to be connected to the IGFET gate to ensure full discharge of the capacitor when the comparator\’s output goes high. When the comparator output is low (input voltage greater than integrator output), the integrator is allowed to charge the capacitor in a linear fashion. The disadvantage of a single slope integrator ADC is the calibration trift dilemma and the solution to this problem is found in a design variation called the dual-slope converter. The layout of single column parallel ADC is illustrated in Fig. Thus, the clock speed error would cancel itself out and the digital output would be exactly what it should be. Imagine we were building a mechanism to measure the rotary speed of a shaft. The input is a voltage, with a range of 0 up to some maximum value that depends on the actual ADC. 195.168.10.9. The proposed EQ based single-slope ADC is designed in standard 130 nm CMOS process with 3.3 V supply voltage. As an example, if the m… The single ADC occupies an area of 6 μm × 465  μm. I … The simple, single-slope run-down is slow. Another important advantage of this method is that the input signal becomes averaged as it drives the integrator during the fixed-time portion of the cycle. Download preview PDF. Thus, shaft speed is our “input signal” to be measured by this device. Instead of using a DAC with a ramped output, we use an op-amp circuit called an integrator to generate a sawtooth waveform which is then compared against the analog input by a comparator. Ramp type ADC 2. Both ADCs make use of simple op-amp circuits and control logic to do most of their work. The accurate correspondence of this ADC\’s output with its input is dependent on the voltage slope of the integrator being matched to the counting rate of the counter (the clock frequency). 1. We choose a single-slope ADC as a candidate for interleaving because of its simplicity, linearity, low-power operation, small area, and small input capacitance. check_circle Expert Answer. Typically, the run down time is measured in clock ticks, so to get four digit resolution, the rundown time may take as long as 10,000 clock cycles. In single-slope integrating ADC on op-amp based circuit, called an integrator to generate a saw tooth wave form is used, instead of the use of a DAC with a ramped output. It is used in the design of digital voltmeter. Hence it is called a s dual slope A to D converter. Dual-slope ADCs are used in applications demanding high accuracy. Depending on a gain value, using a signal greater than ADC saturation, a single slope ADC may be performed. Not logged in 9. Experts are waiting 24/7 to provide step-by-step solutions in as fast as 30 minutes! The ADC’s real-time calibration scheme was proven to greatly improve the converter’s linearity and permit flexible segment setup for a wide range of possible imaging applications. The single-slope ADC suffers all the disadvantages of the digital ramp ADC, with the added drawback of calibration drift. How to do Testing of Junction Field Effect Transistors? 5, since the ramp signal is not generated below the level line L 1 indicating the maximum ADC saturation level of an input signal, a burden of the circuit is reduced or minimized. It is possible to avoid using a DAC if we substitute an analog ramping circuit and a digital counter with precise timing. When the integrator output voltage falls to zero, the comparator output switches back to a low state, clearing the counter and enabling the integrator to ramp up voltage again. Integrator-based design (e.g., single-slope, dual-slope); Sigma-delta design (also known as delta-sigma, 1-bit ADC or oversampling ADC). Figure-5 depicts block diagram of Dual Slope Integrating type ADC. After that, the spring is uncoupled from the shaft and allowed to unwind at a fixed rate, the time for it to unwind back to a relaxed state measured by a timer device. 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