Abstract: Systems and methods for measuring transmitter and/or receiver I/Q impairments are disclosed, including iterative methods for measuring transmitter I/Q impairments using shared local oscillators, iterative methods for measuring transmitter I/Q impairments using intentionally-offset local oscillators, and methods for measuring receiver I/Q impairments. Also disclosed are methods for computing I/Q impairments from a sampled complex signal, methods for computing DC properties of a signal path between the transmitter and receiver, and methods for transforming I/Q impairments through a linear system.

Abstract: Methods and circuits for controlling an automatic gain control (AGC) circuit wherein the AGC circuit is used to adjust the gain of a signal input to an analog to digital converter. The method includes obtaining a plurality of samples from the output of the analog to digital converter and determining whether the amplitude of each sample is greater than a threshold amplitude value. If the amplitude of a sample is greater than the threshold amplitude value then a counter value is incremented. The target average amplitude of the automatic gain control circuit is then periodically adjusted based on the counter value.

Abstract: A data receiving circuit and a data receiving method accurately acquire a data signal corresponding to information data from a high speed high density transmitted signal. An increase or a decrease of the level of one of a amplified data signal and a level converted data signal that is transmitted from one, referred to as one processing stage, of an amplification processing stage and a level converting processing stage, is fed back to a stage preceding the one processing stage. The amplification processing stage supplies, to a first line, an amplified data signal obtained by performing an amplification processing on a received data signal, and the level converting processing stage transmits, via a second line, a level converted data signal obtained by performing a level converting processing on the amplified data signal.

Abstract: Automatic gain control in a receiver. A method for controlling operating range of an analog-to-digital converter (ADC) by an automatic gain control circuit includes estimating a peak-to-average ratio corresponding to an analog signal from digital samples of the analog signal. The method includes determining a peak value corresponding to the analog signal based on the peak-to-average ratio. Further, the method includes maintaining magnitude of the analog signal at an input of the ADC and gain of the receiver based on the peak value.

Abstract: A power adjusting method and apparatus provided by embodiments of the present invention relate to the field of communications. The power adjusting method of this embodiment includes: receiving a signal from a sending end, where the signal includes a cyclic prefix (CP) signal; detecting and acquiring first receiving power and second receiving power of the CP signal, where the first receiving power is average power of N sampling points of the CP signal, and the second receiving power is average power of M sampling points of the CP signal; after determining that a ratio of the first receiving power to target power is greater than a first preset threshold, adjusting signal power magnification; and after determining that the ratio of the second receiving power to the target power is greater than a second preset threshold, adjusting the signal power magnification again.

Abstract: A wireless communication device is disclosed that includes an automatic gain controller capable of accurately adjusting gain of a received signal. The received signal includes a plurality of symbols, including pilot symbols that each includes at least one pilot tone, and data symbols that do not include any pilot tones. A power of a pilot symbol is determined, and a power of a data symbol is determined. The determined data symbol power is then scaled by a scaling factor (that depends on various system parameters) and is subtracted from the determined pilot symbol power to provide an estimate of a power of the pilot tones within the signal. From the estimated pilot tone power, the automatic gain controller can accurately determine a preferred gain for amplifying future frames of the received signal.

Abstract: A semiconductor device is provided, including an input attenuator configured to receive an antenna signal and to output a first attenuated signal, the first attenuated signal corresponding to the antenna signal attenuated by a first attenuation factor, the input attenuator being further configured to receive a control signal and to select one of a plurality of predetermined attenuation factors as said first attenuation factor depending on the control signal; an analog to digital converter configured to generate an intermediate signal by digitizing the first attenuated signal; and a digital attenuator configured to receive the intermediate signal and to output a second attenuated signal, the second attenuated signal corresponding to the intermediate signal attenuated by a second attenuation factor, the second attenuation factor being set so as to compensate a gain quantization error of the control signal.

Abstract: The present invention provides for a circuit with slicing wherein a gain asymmetry variation is decreased across the plurality of mixer slices. In one or more embodiments, a calibration unit can be provided to determine the characteristics of gain asymmetry variation; and a digital compensation unit can be provided to adjust the gain of the circuit over frequency.

Abstract: Described herein is a receiving apparatus and method for receiving signals in a wireless communication system, the signals including a dedicated channel estimation sequence, including a gain control means that controls the gain of a received signal, a channel estimation means that performs a channel estimation on the basis of a dedicated channel estimation sequence included in a received signal, a gain error correction means that corrects a gain error in the result of said channel estimation caused by said gain control means on the basis of the dedicated channel estimation sequence comprised in the received signal, and an equalizing means that performs an equalization on the received signal on the basis of the gain corrected channel estimation result.

Abstract: A mixer, a receiver, and a method provide dynamic sub-sampling mixer which adjust a sub-sampling rate based on power drain and performance. A mixer includes mixer circuitry receiving an input of a Radio Frequency (RF) input signal and providing an output of a baseband signal of the RF input sampled at a sub-sampling rate, baseband parametric control circuitry receiving the baseband signal and measuring at least one parametric value of the baseband signal, and sampling period control circuitry receiving the at least one parametric value and adjusting the sub-sampling rate based thereon, the sub-sampling rate or ratio is adjusted minimize power drain while ensuring performance of the at least one parametric value is satisfying a predetermined level.

Abstract: An antenna amplifier, receiving system, operating method, and use of a receiving system, is provided.

Abstract: A receiver circuit includes an analog front-end circuit, a first adaptation circuit, and a second adaptation circuit. A method operates the receiver circuit. The analog front-end circuit is configured to resolve an output signal from an input signal as a function of adjustable parameters. The first adaptation circuit is coupled to the analog front-end circuit and is configured to determine values of the adjustable parameters responsive to the output signal. The second adaptation circuit is coupled to the analog front-end circuit and to the first adaptation circuit. The second adaptation circuit is configured to adjust the values of the adjustable parameters responsive to one or more operating conditions of the receiver circuit. These operating conditions include a temperature and/or a power supply voltage of the receiver circuit.

Abstract: A communications apparatus is provided. A radio frequency (RF) circuit is arranged to receive an RF signal from an antenna and process the RF signal according to one or more RF parameters to generate an intermediate signal. A signal processing unit is arranged to process the intermediate signal to generate a processed signal and generates signal processing information regarding requirements for processing the intermediate signal. An RF circuit controller is coupled to the RF circuit and the signal processing unit and arranged to dynamically adjust the RF parameters according to the signal processing information.

Abstract: A desired signal and interfering signal are transmitted in the same timeslot and on the same frequency using an Adaptive Quadrature Phase Shift Keying (AQPSK) modulated carrier. When the Sub-Channel Power Imbalance Ratio (SCPIR) for the AQPSK modulated carrier is large and favors the interfering signal, the interfering signal is demodulated first to obtain demodulated soft bits. The demodulated soft bits corresponding to the interfering signal are then used to estimate receiver control parameters, such as Doppler shift, frequency offset, timing error, gain, etc. Using the demodulated soft bits corresponding to the interfering signal improves the accuracy of the receiver control parameters when the SCPIR is large, and results in better overall performance of the receiver.

Abstract: A method for DC offset cancellation includes defining, in a range of possible gain values for operating a direct conversion receiver, multiple sub-ranges of the possible gain values. Multiple DC offset correction values for the respective sub-ranges are stored in a memory. Upon detecting at the receiver that a gain of the receiver has changed from a first sub-range to a second sub-range, DC offset cancellation is initiated based on a DC offset correction value stored for the second sub-range and on a condition relating to past operation in the second sub-range.

Abstract: A receiver device for receiving a signal that comprises one or more periodic features, the receiver device comprising: a detector configured to listen to the signal during at least a first reception phase, and to be triggered when a feature of the signal is received so as to determine the time of reception of that feature; and a receiver configured to process time-limited segments of the signal so as to derive information from features of the signal received during those segments, the receiver being configured to be dependent on the detector such that after the first reception phase the timings of the time-limited segments processed by the receiver are dependent on the time of reception determined by the detector.

Abstract: A radio receiver (100) comprises an analogue to digital converter (30) for generating a data word representative of a received radio signal and a gain control stage (40) comprising a first register (42) for storing the data word. The gain control stage (40) is adapted to control the numerical value of the data word by controlling the position of the data word in the first register (42).

Abstract: A method of identifying radar in a wireless device includes detecting an event corresponding to receipt of a signal by the wireless device. The event can include an analog to digital converter (ADC) saturation, a radio frequency (RF) saturation, and/or an ADC power high condition. Notably, the gain change in the wireless device is delayed for a first predetermined time period. Data preceding the event for the first predetermined time period can be buffered. A first low-resolution fast Fourier transform (FFT), wherein low-resolution FFTs are referred to as short FFTs, can be performed with the buffered data. The first short FFT can be processed. When results of the processing indicate the signal is radar, the radar can then be identified.

Abstract: A communication device includes: an amplifier (62) arranged to amplify a reception signal received from one of the plurality of terminals; a first demodulation unit (26) arranged to demodulate a first frame transmitted using a first communication method operable to communicate when CNR is smaller than 0 dB; a second demodulation unit (27) arranged to demodulate, in parallel with the first demodulation unit demodulating the first frame, a second frame transmitted using a second communication method having a rate higher than a rate of the first communication method at a frequency band same as a frequency band used for the first communication method; and a gain controller (64) arranged to adjust a gain of the amplifier in accordance with a detection outcome of a preamble included in the first frame and the second frame.

Abstract: An embodiment of the present invention provides a method for digital television demodulation, comprising using adjacent-channel power dependent automatic gain control (AGC) for the digital television demodulation, wherein an AGC technique takes into account a total power as well as power of adjacent channels to control gain of a gain control amplifier.

Abstract: When a decision is made that receiving performance deterioration due to an interfering wave is present in a digital broadcasting wave, an operating point of an RF AGC amplifier 6 and a time constant of gain control of the RF AGC amplifier 6 are altered.

Abstract: In a signal-based gain control scheme, one or more gain levels used for processing signals are selected based on characteristics of previously received signals. For example, different gain levels may be used to receive sets of signals whereupon certain characteristics of the received sets of signals are determined. One or more gain levels are then selected based on these characteristics whereby another signal is processed based on the selected gain level(s). In some aspects, the signal-based gain control scheme may be employed to facilitate two-way ranging operations between two devices. For example, leading edge detection may involve determining a characteristic of a received signal, determining a threshold based on the characteristic, and identifying a leading edge associated with the received signal based on the threshold. In some aspects, the signal-based gain control scheme may be employed in an ultra-low power pulse-based communication system (e.g., in ultra-wideband communication devices).

Abstract: Data transmission is disclosed over a transmission channel that is subject to narrowband interferers. An increased overall bit or data transmission rate is achieved by an exemplary method of determining a channel capacity of plural sub-channels of the transmission channel based on a net background noise power estimation. The net background noise power contains only white noise-like contributions and excludes, to a reasonable extent, noise contributions or signal power from narrowband interferers. Hence, the net background noise power can be reduced. For example, an Orthogonal Frequency Division Multiplex (OFDM) signal code construction or bit allocation scheme can be chosen that provides for optimized data transmission at a data rate that approximates or approaches the more realistic channel capacity of an individual sub-channel, resulting in an increased overall bit or data transmission rate.

Abstract: An apparatus and method for automatically controlling a gain in a portable communication system are provided. The apparatus includes a channel determiner for controlling a fading margin depending on the channel variation amount to control the limited total dynamic range of the ADC.

Abstract: Provided are a receiving apparatus and method for a wireless communication system using multiple antennas. A receiving method for a wireless communication system using multiple paths, the receiving method comprising: receiving signals through a predetermined number of multiple paths; sensing a carrier according to saturation state degrees of the signals, and providing saturation state information; calculating automatic gain components of the received signals by using the received signals and the saturation state information of the received signals; and performing a noise matching process to amplify noises on the predetermined multiple paths according to the automatic gain components during a predetermined period.

Abstract: A receiver device detects a plurality of symbols in a signal and determines, based on the one of the plurality of detected symbols, an estimated beginning of a subsequent frame. The receiver device determines whether the estimated start of the subsequent frame corresponds to an actual start of the subsequent frame. When the estimated start of the subsequent frame corresponds to the actual start of the subsequent frame, the receiver is synchronized to the actual start of the frame. When the estimated start of the subsequent frame does not corresponds to the actual start of the subsequent frame, the receiver device determines, based on a further one of the plurality of detected symbols, an estimated beginning of another subsequent frame. The receiver device determines whether the estimated start of the other subsequent frame corresponds to an actual start of the other subsequent frame.

Abstract: Methods and apparatuses for reducing DC offsets in a communication system are described. In a first aspect, a feedback loop circuit reduces DC offset in a wireless local area network (WLAN) receiver channel. The frequency response of the feedback loop circuit can be variable. In a second aspect, a circuit provides gain control in a WLAN receiver channel. The stored DC offset is subtracted from the receiver channel. First and second automatic gain control (AGC) amplifiers are coupled in respective portions of the receiver channel. In a third aspect, a feedback loop circuit reduces DC offset in a WLAN receiver channel. The feedback loop circuit includes a storage element that samples and stores receiver channel DC offset. The loop is opened, and the DC offset stored in the storage element is subtracted from the receiver channel. Circuits for monitoring DC offset, and for providing control signals for controlling the frequency response of the DC offset reducing circuits are also provided.

Abstract: Suitable gain control is achieved at low cost. In a receiving apparatus, an RF signal that is amplified by an RF amp is converted to an IF frequency by a frequency conversion unit and amplified by an IF amp, then the output signal from the IF amp that was converted to a digital signal by an ADC is inputted to a digital processing unit. The output from the ADC is then filtered to a desired frequency by a digital filter and inputted to the digital processing unit. In the digital processing unit the signal power before filtering by the digital filter and the signal power after filtering by the digital filter are measured, and the power difference is calculated. Based on the power difference, which indicates the ratio of unnecessary power, the digital processing unit controls the gain ratio of the RF amp and IF amp.

Abstract: Interference in a wireless communication system receiver, such as at a base station, is identified based on monitoring automatic gain control (AGC) events. AGC statistics in combination with base band processing are used to identify the interference. Performance degradation is evaluated, and interference mitigation solutions are proposed based on the identified interference. Mitigation solutions include IRC, scheduling restrictions, and filter modifications including replacement of filters.

Abstract: A signal reception apparatus in a communication system supporting a beam forming scheme is provided. The signal reception apparatus includes a Low Noise Amplifier (LNA) configured to generate a second signal by amplifying a first signal according to a first gain value, a Variable Gain Amplifier (VGA) configured to generate a third signal by amplifying the second signal according to a second gain value, and an Automatic Gain Controller (AGC) configured to control the first gain value and the second gain value by considering a plurality of beam types supported in a signal transmission apparatus.

Abstract: A novel receiver architecture optimizes receiver performance in the presence of interference. In various embodiments, power estimation circuits are used with variable selectivity to determine the exact nature of the interference and to optimize the performance correspondingly. The variable selectivity is achieved using stages of filtering with progressively narrower bandwidths. Also, the actual method of optimizing the receiver performance is novel compared to the prior art in that the gain settings and the baseband filter order (stages to be used) will be optimized based on the nature of the interference as determined by the power detector measurements. For a device such as a cellular phone that operates in a dynamic and changing environment where interference is variable, embodiments advantageously provide the capability to modify the receiver's operational state depending on the interference.

Abstract: Techniques for performing analog calibration of a receiver to optimize a second-order input intercept point (IIP2). In an aspect, a signal generator modeling an interferer is coupled to an adjustable input of a receiver, e.g., a gate bias voltage of a mixer. For example, the signal generator output may be a single-tone on-off keying (OOK) modulated signal. The mixer mixes the signal down to baseband, wherein an analog correlator correlates the down-converted signal with the known sequence of bits used to perform the OOK modulation. The analog correlation output is then provided to drive the bias voltage in the mixer, e.g., one or more gate voltages of transistors in the differential mixer, to optimize the overall receiver IIP2. Further aspects of the disclosure provide for calibrating receivers having multiple LNA's, and also dual or diversity receivers having multiple receive paths.

Abstract: The invention discloses a system comprising a first device and a plurality of second device. The system comprises a first device and a plurality of second devices. The first device comprises a receiver, a spectrum analyzer, a controller and a transmitter. The receiver receives, from at least one antenna, a plurality of signals with different signal strengths from different sources. The spectrum analyzer is communicatively coupled to the receiver and obtains strengths of the plurality of received signals. The controller is communicatively coupled to the spectrum analyzer and adjusts a radiation feature of one of at least one antenna to minimize a difference of the strengths between a plurality of received signals after adjustment. The transmitter transmits the received signals after adjustment to a plurality of second devices distributed within a site. The plurality of second devices transmit the plurality of received signals after adjustment within the site.

Abstract: A radio frequency (RF) front-end circuit and an operating method thereof are provided. The proposed RF front-end circuit includes a first linear amplifier, a second linear amplifier, and a calibration unit. The first linear amplifier performs a high-frequency amplification on a RF signal to generate an amplified RF signal, and down-converts the amplified RF signal into an intermediate frequency (IF) signal. The second first linear amplifier performs a low-frequency amplification on the IF signal to generate an amplified IF signal. The calibration unit is coupled to the first and the second linear amplifiers, and receives a voltage gain fed back from the second linear amplifier. Then, the calibration unit performs an auto-calibration procedure according to the voltage gain fed back from the second linear amplifier to search for an input current value of the first linear amplifier, which correspondingly maximizes the voltage gain of the first amplifier.

Abstract: This disclosure is directed to wireless communication systems having a receiver configured to search for transmitted packets using a single chain and then receive the transmitted packets using multiple chains. Such receivers feature a chain controller that operates a single chain during search mode and turns on additional chains after packet detection. As will be appreciated, the techniques of this disclosure take advantage of the structure of the mixed mode data packet preamble to allow multiple chains to be brought on line after detection of a packet by a single chain.

Abstract: Based on tracked amplitude modulation (e.g., which may be hum modulation), compensation for amplitude modulation is applied across all orthogonal signal components of a non-time based orthogonal coded signal. Some examples of such non-time based orthogonal coded signals include an orthogonal frequency division multiplexing (OFDM) signal, a synchronous code division multiple access (S-CDMA) signal, or a code division multiple access (CDMA) signal, etc. The compensation may be applied to the signal across multiple frames, on a frame by frame basis, or intra-frame (i.e., changing and compensating differently within a frame). This compensation for amplitude modulation may be applied in conjunction with adaptive equalization in which different filter taps are applied to each respective orthogonal signal component of the signal. Also, automatic gain control (AGC) may be performed (e.g., before digital sampling) of a received signal in conjunction with the amplitude modulation compensation.

Abstract: In one embodiment, the present invention includes a method for receiving a radio frequency (RF) signal and mixing the RF signal with a master clock to obtain a mixed signal, cyclically rotating the mixed signal to each of N gain stages for at least one cycle of the master clock, and summing the outputs of the N gain stages to provide an output signal.

Abstract: A system for selectively and discretely amplifying or attenuating antennas in a hybrid multiple-input-multiple-output (MIMO) radio distribution network (RDN) receiving system is provided herein. The system includes a MIMO receiving system comprising a MIMO baseband module having N branches; an RDN connected to the MIMO receiving system, the RDN comprising at least one beamformer fed by two or more antennas, so that a total number of antennas in the system is M, wherein M is greater than N, wherein each one of the beamformers include a passive combiner configured to combine signals coming from the antennas coupled to a respective beamformer into a combined signal, wherein the at least one beamformer is further configured to selectively amplify or attenuate in discrete steps, one or more of the signals coming from the M antennas, based on qualitative metrics measured by the MIMO baseband module.

Abstract: A method and apparatus for a receiver system in a receiver that includes at least two front end branches, each branch having its own intermediate frequency (IF) mixer to shift a received signal to an IF. When receiving multiple independent signals, the signals are digitized and the receiver performs a digital complex transform on each signal to obtain the corresponding quadrature component. When receiving a single signal the signal is routed to two mixers that are 90 degrees out of phase to obtain the quadrature signal components in the analog section of the receiver.

Abstract: In one embodiment, the present invention includes a method for receiving a radio frequency (RF) signal and mixing the RF signal with a master clock to obtain a mixed signal, cyclically rotating the mixed signal to each of N gain stages for at least one cycle of the master clock, and summing the outputs of the N gain stages to provide an output signal.

Abstract: The purpose of the present invention is to shorten a time required to perform Auto Gain Control (AGC) processing in a wireless device that can be applied to a plurality of wireless systems. On the basis of a first gain adjusted by means of a gain control unit (450-1), an initial gain setting unit (460) sets, for a variable gain unit (432-2), an initial gain (converted second initial gain) at the start of gain adjustment. Then, a gain control unit (450-2) sets the initial gain to a second gain at the time of starting the gain adjustment, and adjusts the second gain on the basis of IQ signals of a system, the IQ signals having the level adjusted by means of the variable gain unit (432-2).

Abstract: An analog front circuit for a medical device includes an automatic gain control loop and a 2-order-3-bit-quantization Sigma-Delta analog-to-digital converter. The automatic gain control loop is configured to implement automatic control of loop gain and output an analog signal to the 2-order-3-bit-quantization Sigma-Delta analog-to-digital converter. The 2-order-3-bit-quantization Sigma-Delta analog-to-digital converter is configured to convert the analog signal output from the automatic gain control loop into a digital code and output the digital code to a DSP for processing.

Abstract: A circuit for a receiver with reconfigurable low-power or wideband operation may comprise one or more main signal paths each coupled to a first port and including a low-noise amplifier (LNA) configured to provide a radio frequency (RF) signal to a main mixer circuit. An auxiliary signal path may be coupled to a second port. The auxiliary signal path may include an auxiliary mixer configured to provide an on-chip matching input impedance that may match an impedance of the antenna. The first port may be coupled to an RF antenna through an off-chip matching circuit, when a low-power operation is desired. The first port may be coupled to the second port and to the RF antenna, when a wideband operation is desired.

Abstract: A receiver including a mixer configured to generate (i) a first output and (ii) a second output, a first capacitance coupled to the first output, and a second capacitance coupled to the second output, A controller is configured to program (i) the first capacitance and (ii) the second capacitance to a first capacitance value in response to operating the receiver in a first mode, and program (i) the first capacitance and (ii) the second capacitance to a second capacitance value in response to operating the receiver in a second mode. The first capacitance value determines one or more of (i) linearity, (ii) gain, and (iii) noise figure of the receiver in the first mode. The second capacitance value determines one or more of (i) linearity, (ii) gain, and (iii) noise figure of the receiver in the second mode.

Abstract: A basic idea is to determine (S1) occurrence of a glitch caused by operation of the AGC mechanism, identify (S2) those modulation symbols in a digitized version of the received signal that are affected by the glitch, each modulation symbol represented by a number of bits in combination, and then reduce (S3), for each of the identified modulation symbols, the contribution in representing the identified modulation symbol as provided by at least a subset of the bits of the modulation symbol. In this way, the adverse effects of the glitch can be effectively mitigated and subsequent detection of the desired signal can be significantly improved. This also means that the link performance will be significantly improved.

Abstract: A switching scheme is used during a calibration mode for determining calibration coefficients of each calibrated stage of a pipeline analog-to-digital converter (ADC). A calibrated stage of the pipeline ADC includes an amplifier for amplifying a residue voltage of the stage and a sampling capacitor comprising a plurality of sub-capacitors. The plurality of sub-capacitors have a first terminal connected to an input of amplifier and a second terminal connected to one or more switches that selectively couple the second terminal to the input terminal of the stage, a first reference voltage or a second reference voltage lower than the first reference voltage. During foreground calibration, a number of measurements are taken at an output of the amplifier to determine the calibration coefficient of the calibrated stage.

Abstract: VGAs amplify a baseband reception signal using a prescribed gain. HPFs stop part, in a band lower than a first cutoff frequency, of the amplified reception signal. An ADC AD-converts an output signal of the HPFs and thereby outputs a digital reception signal. An AGC controller outputs a gain code corresponding to a prescribed gain of the VGAs. A VGA gain corrector adjusts the gain of the VGAs by a prescribed amount.

Abstract: Apparatuses, methods and systems of selecting a gain setting of a receiver chain are disclosed. One method includes bypassing a filter portion of the receiver chain and sampling a bypass receive signal while the filter portion of the receiver chain is bypassed. If the sampled bypass receive signal is determined to be saturated greater than a threshold, then selecting a gain setting of the receive chain as a function of the saturation. Further, the filter portion of the receive chain is included while sampling a receive signal with the selected gain setting.

Abstract: A gain control circuit adjusts the signal level of a received signal responsive to the bandwidth a received signal and/or the delay spread of the channel in which the signal has propagated. The bandwidth and delay spread are evaluated to estimate the amount of signal variation that is expected due to fast fading. Adjustments to the signal level are then made to avoid clipping while at the same time ensuring that the dynamic range of a receiver component is efficiently utilized.

Abstract: According to an embodiment, there are provided a capacitor DAC for generating an output signal in accordance with a connection state of a capacitor element, a reference voltage generation circuit for supplying a reference voltage to the capacitor DAC, a comparator for outputting a comparison result in accordance with the output signal, a successive approximation register for outputting a digital signal in accordance with the comparison result, and a control circuit for controlling a connection state of the capacitor element in accordance with the comparison result and comparing an ideal code with a digital signal obtained by sampling a predetermined voltage, thereby correcting an error of the digital signal.