Differential amps have 94dB minimum CMRR
- Autor:Ella Cai
- Solte em:2018-08-15
Analog Devices has released a set of differential-in differential-out amplifiers win a minimum CMRR (common-mode rejection ratio) of 94dB.
Based on the existing LTC6363 differential amplifier which needs external resistors, they have built-in matched resistors. “Resistor matching is equivalent to a 0.002%. Initial gain accuracy is 45ppm maximum and varies by only 0.5ppm/°C maximum over temperature,” said the firm. “The precision resistors have been designed with overall system performance in mind, striking a balance between noise and linearity, and utilising laser trimmed factory calibration.”
The three parts are LTC6363-0.5, LTC6363-1 and LTC6363-2 with, respectively, fixed gains of 0.5, 1 and 2V/V. While the original LTC6363 was available in both 3 x 5mm MSOP and 2 x 3mm DFN packages, the new parts only come in MSOP.
Operation for the entire LTC6363 family is from supplies between 2.8V and 11V (±1.4V to ±5.5V) – while typically drawing 1.75mA – and from -40°C to 125°C.
Product design manager Maziar Tavakoli sees the amplifier’s balance of power consumption noise and linearity and precision meeting driving needs of high performance successive-approximation analogue to digital converters.
“For example, the LTC2378-20 20bit SAR ADC consumes 21mW at 1Msample/s,” he said. “The LTC6363 family’s noise and linearity have negligible impact on ADC performance while consuming a mere 19mW, comparable to the ADC’s power consumption. Now with the LTC6363-0.5, LTC6363-1 and LTC6363-2 you can get this same ADC driving performance plus the added precision afforded by the precision integrated resistors.”
Driving 20bit ΣΔ ADCs is another use.
LTC6363-x.x series:
Based on the existing LTC6363 differential amplifier which needs external resistors, they have built-in matched resistors. “Resistor matching is equivalent to a 0.002%. Initial gain accuracy is 45ppm maximum and varies by only 0.5ppm/°C maximum over temperature,” said the firm. “The precision resistors have been designed with overall system performance in mind, striking a balance between noise and linearity, and utilising laser trimmed factory calibration.”
The three parts are LTC6363-0.5, LTC6363-1 and LTC6363-2 with, respectively, fixed gains of 0.5, 1 and 2V/V. While the original LTC6363 was available in both 3 x 5mm MSOP and 2 x 3mm DFN packages, the new parts only come in MSOP.
Operation for the entire LTC6363 family is from supplies between 2.8V and 11V (±1.4V to ±5.5V) – while typically drawing 1.75mA – and from -40°C to 125°C.
Product design manager Maziar Tavakoli sees the amplifier’s balance of power consumption noise and linearity and precision meeting driving needs of high performance successive-approximation analogue to digital converters.
“For example, the LTC2378-20 20bit SAR ADC consumes 21mW at 1Msample/s,” he said. “The LTC6363 family’s noise and linearity have negligible impact on ADC performance while consuming a mere 19mW, comparable to the ADC’s power consumption. Now with the LTC6363-0.5, LTC6363-1 and LTC6363-2 you can get this same ADC driving performance plus the added precision afforded by the precision integrated resistors.”
Driving 20bit ΣΔ ADCs is another use.
LTC6363-x.x series:
- Differential rail-to-rail outputs
- Input common-mode range includes ground
- 0.5V/V, 1V/V, or 2V/V fixed gain
- 2.9nV/√Hz input-referred noise
- 45ppm max gain error
- 0.5ppm/°C max gain error drift
- 94dB min CMRR
- 100μV max input offset
- 50nA max input offset
- 720ns settling to 18bit (8Vp-p output)
- 118dB SFDR (2kHz 18Vp-p)
- 500MHz gain.bandwidth
- 35MHz bandwidth (–3dB)
- 2.8V to 11V (±1.4V to ±5.5V) supply
- 2mA max supply
- 20μA shut-down (3V supply)
- 8-pin MSOP
