MAT04EY Просмотр технического описания (PDF) - Analog Devices

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MAT04EY

Matched Monolithic Quad Transistor

Analog Devices 

MAT04

Figure 5. Vector Summer

LOW NOISE, HIGH SPEED INSTRUMENTATION

AMPLIFIER

The circuit of Figure 6 is a very low noise, high speed amplifier,

ideal for use in precision transducer and professional audio

applications. The performance of the amplifier is summarized in

Table I. Figure 7 shows the input referred spot noise over the

0–25 kHz bandwidth to be flat at 1.2 nV/√Hz. Figure 20 high-

lights the low 1/f noise corner at 2 Hz.

The circuit uses a high speed op amp, the OP17, preceded by

an input amplifier. This consists of a precision dual matched-

transistor, the MAT02, and a feedback V-to-I converter, the

MAT04. The arrangement of the MAT04 is known as a “linear-

ized cross quad” which performs the voltage-to-current conversion.

The OP17 acts as an overall nulling amplifier to complete the

feedback loop. Resistors R1, R2, and R3, R4 form voltage divid-

ers that attenuate the output voltage swing since the “cross

quad” arrangement has a limited input range. Biasing for the in-

put stage is set by Zener diode Z1. At low currents, the effective

zener voltage is about 3.3 V due to the soft knee characteristic of

the Zener diode. This results in a bias current of 530 µA per

side for the input stage. The gain of this amplifier with the val-

ues shown in Figure 6 is:

VOUT = 33000

VIN

RG

Table I. Instrumentation Amplifier Characteristics

Input Noise

Voltage Density

G = 1000

G = 100

G = 10

1.2 nV/√Hz

3.6 nV/√Hz

30 nV/√Hz

Bandwidth

G = 500

G = 100

G = 10

400 kHz

1 MHz

1.2 MHz

Slew Rate

40 V/µs

Common-Mode Rejection G = 1000

130 dB

Distortion

G = 100

f = 20 Hz to 20 kHz 0.03%

Settling Time

G = 1000

10 µs

Power Consumption

350 mW

–8–

REV. D

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