The two indexes of ADC chip, speed and precision, are mutually restricted. High speed / high-precision ADC has always been the direction of efforts of domestic manufacturers. After all, ADC is too critical to connect the real analog world with electronic systems. With the national attention to the integrated circuit industry, China’s chip industry has developed rapidly in recent years, and many domestic ADC chips have come into our sight. These high-quality domestic ADC manufacturers have launched many representative series that are not inferior to the products of international ADC head manufacturers, and completed some domestic replacement of ADC.



Xinhai Technology High Precision ADC series



Xinhai technology mainly focuses on high-precision ADC. Since 2003, it has started its own research. In 2006, it launched a 24bit high-precision low-power ADC chip CS1242 to fill the market gap. Up to now, the cs12xx series of Xinhai Technology is a well-known series of domestic high-precision ADC. Depending on its high precision, high input impedance and low power consumption, this series has been applied in many scenarios (Pan health devices, smart phones, smart homes, industrial measurement, automotive electronics).



Cs1232 is the model with the highest effective accuracy in this series at present. ENOB can reach 23.5 bits at most. It is a frequent customer in high-precision measurement applications.

(source: Xinhai Technology)


Cs1232 adopts a third-order sigma delta modulator to realize PGA amplification through a low-noise instrument amplifier structure. The amplification factor can be 1, 2, 64128. Its output rate is 10hz/80hz. P-P noise is 139nv at 10Hz and 298nv at 80Hz. Cs1232 has built-in RC oscillator, which can use external crystal oscillator or input clock directly through pins.



When the PGA is 128, the integral linearity of the whole system is ± 6ppm, and the gain error does not exceed ± 0.1%. The power consumption of the whole system is also low. According to the current in power down mode, the current of analog part is only 0.1ua, and that of digital part is only 1.5ua. In the high-precision ADC category, such performance and power consumption indicators are also outstanding.



Xinbaiwei ADC



Xinbaiwei’s ADC is mostly used in radar system, power grid and other fields. The accuracy and rate cover a wide range. The architecture also covers SAR, pipeline and sigma delta. If one of the most memorable ADCs in these ranges is selected, it is the cbm08ad1500qp with high sampling rate of Xinbai micro.

(source: xinbaiwei)


Cbm08ad1500qp, dual channel 8-bit ultra-high speed ADC. Cbm08ad1500qp has a maximum sampling rate of 1.5gsps per channel. It can reach twice the sampling rate by using time alternating mode. It has great advantages in high-speed digital acquisition, radar and communication receiving applications.



Cbm08ad1500qp is a structure combining folding and interpolation. It contains sample / hold amplifier, folding amplifier, bandgap voltage reference, clock circuit and LVDS output circuit. The output clock provides SDR and DDR selection and clock duty cycle correction. This series does not realize high sampling rate at the expense of power consumption and accuracy. The devices are specially optimized at high sampling rate, and can achieve excellent DC linearity and AC performance even at full throughput.



Fast core micro ultra high speed ADC



Suzhou XunXin microelectronics focuses on ultra-high speed, mainly making high-speed ADC with 6-14 bit resolution. It is in the leading position in China in terms of high speed. Its aad08q2500 is a 4-channel 8-bit ADC representative product, and the sampling rate can reach 10gsps.

(source: XunXin micro)


Aad08q2500 adopts Si based process, which can convert differential 400mV input analog signal into 8bit digital signal. The chip contains four sub ADCs working at a maximum of 2.5gs/s. These sub ADCs can operate in interleaved or non interleaved mode and are configured as four channel, two channel or single channel.



The aad08q2500 analog input bandwidth is 3.8ghz, the overall SFDR index of the device is 40dB, and the ENOB is 5.5bits. The chip is powered by +3.3v/+1.8v power supply, and the total power consumption is about 8.5W. The chip is packaged in flip chip BGA and has 392 pins. In the domestic ultra-high speed ADC field, the device has good technical advantages. At present, it is developing towards integrated ADC chips.



Medium micro high precision ADC



The MCU of the micro enterprise adopts the self-developed ADC. Although there are not many models of the cms24ad series, it has good performance in high-precision applications.

(Figure source: Zhongwei semiconductor)


Cms24ad2001 has a wide range of PGA amplification. Sigma delta modulator is also used to realize PGA amplification through low-noise instrument amplifier structure. When the PGA is 128, its ENOB 20.6 bit is flush with other similar domestic ADCs. At this time, the equivalent input noise is 30nvrms.



In normal operation mode, ADC data output rate is optional, covering 2.5hz-2.56khz. The gain error is about ± 1.5%, and the gain error drift is 16ppm/ ℃, which is slightly higher. The overall power consumption of the device is at a low level. When the PGA is 128, the normal working current is 1.68ma, and the sleep mode current does not exceed 50na. It is a low-power ADC device with high precision.



Summary



ADC itself requires a certain amount of technical accumulation. At the same time, it also needs constant iteration and tempering. This is not easy. Domestic ADC impressed us deeply, but we should also recognize that there is still a gap between China’s ADC chip technology and European and American enterprises in the high-end field, which is also the driving force for domestic ADC manufacturers to make breakthroughs.

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