Rad-tolerant 36V instrumentation amplifier with differential ADC driver

July 12, 2016 // By Graham Prophet
Intersil’s ISL70617SEH has been designed to maximise sensor signal processing performance in communication satellite applications; it is a radiation tolerant 36V instrumentation amplifier (in-amp) featuring an integrated differential analogue-to-digital converter (ADC) driver.

The differential input, rail-to-rail output in-amp offers signal processing performance for low-level sensor telemetry data critical to communication satellites. High integration reduces system size, weight and power (SWAP) costs, and accelerates time to market.


The ISL70617SEH claims higher common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) than alternatives, at all gain settings. Designers can program the in-amp’s gain from 0.1 to 10,000 using two external resistors. The device is wafer-by-wafer guaranteed to 75 krad (Si) with a low dose rate exposure of 10 mrad/sec, which more closely resembles the space environment than the high dose rate testing used with other devices. The ISL70617SEH uses Intersil’s silicon on insulator process to provide single event latch-up (SEL) and single event burnout (SEB) robustness of 60 MeV in heavy ion environments. Its single event transient (SET) performance of <10 µsec eliminates the need for extra filtering.


The ISL70517SEH joins the ISL70617SEH, and offers similar features but implements a differential input and rail-to-rail single-ended output. Both in-amps allow designers to power the input/output stages from different supplies using individual power supply pins. Designers are able to take the input signals riding on a high common-mode voltage and level shift them to a low voltage device. For example, Intersil’s in-amps can protect downstream ICs from high voltage signals by tying the amplifier’s rail-to-rail output to an ADC’s low voltage power supply. This also preserves the ADC maximum input dynamic range and eliminates ADC input overdrive.


Features include

• Low input offset of 30 µV, and low input bias current of 0.2 nA

• CMRR and PSRR of 120 dB typical for attenuating, gaining and filtering sensor signals to improve signal quality

• Operating range from ±4V to ±18V covers the majority of analogue supply rails

• Closed loop -3 dB BW 0.3 MHz (AV = 1k) to 5.5 MHz (A = 0.1)

• Extended operating temperature range of -55°C