Intersil ISL55210 Wideband Differential Amplifier
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The ISL55210 is a very wide band, Fully Differential Amplifier (FDA) intended for high dynamic range ADC input interface applications. This voltage feedback FDA design includes an independent output common mode voltage control.
Intended for very high dynamic range ADC interface applications, at the lowest quiescent power (115mW), the ISL55210 offers a 4.0GHz Gain Bandwidth Product with a very low input noise of 0.85nV/√(Hz). In a balanced differential I/O configuration, with 2VP-P output into a 200Ω load configured for a gain of 15dB, the IM3 terms are <-100dBc through 110MHz. With a minimum operating gain of 2V/V (6dB), the ISL55210 supports a wide range of higher gains with minimal BW or SFDR degradation. Its ultra high differential slew rate of 5,600V/μs ensures clean large signal SFDR performance or a fast settling step response.
The ISL55210 requires only a single 3.3V (max 4.2V) power supply with 35mA typical quiescent current. This industry leading low current solution can be further reduced when needed using the optional power shutdown to <0.4mA supply current. External feedback and gain setting resistors give maximum flexibility and accuracy. A companion device, the ISL55211, includes on-chip feedback and 3 possible gain setting connections where an internally fixed gain solution is preferred. The ISL55210 is available in a leadless, 16 Ld TQFN package and is specified for operation over the -40°C to +85°C ambient temperature range.
Key Features
- Gain Bandwidth Product: 4.0GHz
- Input Voltage Noise: 0.85nV/√(Hz)
- Differential Slew Rate: 5,600V/μs
- 2VP-P, 2-tone IM3 (200Ω) 100MHz: -109dBc
- Supply Voltage Range: 3.0V to 4.2V
- Quiescent Power (3.3V Supply): 115mW
Benefits for Instrumentation
- 4.0GHz GBWP can accommodate high frequencies of interest
- Fast slew rate does not distort the signal
- Minimal performance degradation of ADCs up to 16-bit resolution
That last stage interface to the ADC must support the full input swing for the ADC often including a bit of insertion loss from an interstage filter – one example shown. This filter helps improve the SNR by limiting the broadband noise up to the ADC but is of course optional.
While there are many FDA’s in the market, none match the 3rd order intermodulation distortion (IM3) performance vs quiescent power. Most earlier solutions reaching this level of performance exceeded 500mW while the ISL55210 hold < 115mW.