AD8421 Instrumentation Amplifier Module Millivolt microvolt small signal Single / Dual power supply for Ham Radio amplifier |

AD8421 Instrumentation Amplifier Module Millivolt microvolt small signal Single / Dual power supply for Ham Radio amplifier |

Description:

Features:


The AD8421 is a low cost, low power, extremely low noise,
ultralow bias current, high speed instrumentation amplifier
that is ideally suited for a broad spectrum of signal
conditioning and data acquisition applications. This product
features extremely high CMRR, allowing it to extract low
level signals in the presence of high frequency common-mode
noise over a wide temperature range.


The 10 MHz bandwidth, 35 V/μs slew rate, and 0.6 μs settling
time to 0.001% (G = 10) allow the AD8421 to amplify high
speed signals and excel in applications that require high
channel count, multiplexed systems. Even at higher gains,
the current feedback architecture maintains high
performance; for example, at G = 100, the bandwidth is 2 MHz
and the settling time is 0.8 μs. The AD8421 has excellent
distortion performance, making it suitable for use in
demanding applications such as vibration analysis.


The AD8421 delivers 3 nV/√Hz input voltage noise and 200 fA/√Hz
current noise with only 2 mA quiescent current, making it an
ideal choice for measuring low level signals. For
applications with high source impedance, the AD8421 employs
innovative process technology and design techniques to
provide noise performance that is limited only by the
sensor.


The AD8421 uses unique protection methods to ensure robust inputs while
still maintaining very low noise. This protection allows
input voltages up to 40 V from the opposite supply rail
without damage to the part. A single resistor sets the gain
from 1 to 10,000. The reference pin can be used to apply a
precise offset to the output voltage.


The AD8421 is specified from −40°C to +85°C and has typical
performance curves to 125°C. It is available in 8-lead MSOP
and SOIC packages.


Technical index

1. Low power consumption:

The maximum power supply current is 2.3 mA.

2. Low noise:

The maximum input voltage noise at 1 kHz is 3.2 nV/√Hz;

Current noise at 1 kHz: 200 fA/√Hz (at 1 kHz).

3. Excellent communication characteristics:

Bandwidth: 10 MHz (G = 1);

Bandwidth: 2 MHz (G = 100);

0.001% settling time: 0.6 µs (G = 10);

Common mode rejection ratio (CMRR): 80 dB (20 kHz, G = 1).

35 V/µs slew rate

4. High precision DC performance (AD8421BRZ)

CMRR: 94 dB (minimum value, G = 1)

Input offset voltage drift: 0.2 µV/°C (maximum)

Maximum gain drift: 1 ppm/°C (G = 1)

Input bias current: 500 pA (maximum)

5. Wide power supply range:

5V to 36 V single power supply;

Dual power supply: ±2.5 V to ±18 V.

6. Input overvoltage protection:

Input overvoltage protection can exceed 40V of reverse power
supply

7. Gain:

The gain is set by a single resistor (G = 1 to 10,00)

Default delivery: 10 times gain, you can adjust the gain
through the potentiometer.

Fourth, the schematic diagram of the module (provided after
purchase)



Schematic description:

1. Adopt single power supply mode:

If the input signals (IN- and IN+) are in the range of 0~VCC
positive power supply (including DC bias differential
signal), the module only needs a single power supply. At
this time, disconnect J10, J11; connect J7, J8, J6. At this
time, the module is working in a single power supply state,
and the DC bias voltage can be input from the SMA3 (or J4)
end (or J6 is connected, and the bias voltage is set by the
potentiometer).

2. Adopt dual power supply mode:

The input voltage is dual power supply, the default
delivery: disconnect J7, J11; connect J10, J8

The input voltage is a single power supply and requires
negative voltage module conversion. The default delivery:
disconnect J5; connect J10, J11, J8, J6

If the input signal (IN- and IN+) contains negative voltage
components or pure AC signals, the module needs dual power
supply. At this time, turn off J7; turn on J8, J10, J11, and
the module is working in dual power state. SMA3 (or J4)
terminal input DC bias voltage, (or turn on J7, the bias
voltage is set by the potentiometer).

Output signal Vout=[(Vin+)-(Vin-)]*G+Vref

G = 1 + (9.9 kΩ/RG)