Overview

The AD630 is a balanced modem with a high dynamic range. When configured as a lock-in amplifier, the AD630 can recover small signals from l00dB of interfering noise. Its internal phase-sensitive detector is based on a switch-multiplied architecture. To ensure its operation The accuracy and stability of the internal resistance are preclude the use of high-precision SiCr film resistors, the internal integrated compensation capacitor, only need to connect the chip pin to work stable in the closed-loop gain. The integrated resistor network within the chip can be configured to ± 1 and ± 2 precision closed-loop gain. You can also preclude the use of external feedback resistor method to achieve the special requirements of the function.

Second, the characteristics

1. Can recover from 100 dB noise signal

2. Bandwidth: 2 MHz channel bandwidth

3. Slew rate: 45 V / us

4. Low crosstalk: -120 dB at 1 kHz and -100 dB at 10 kHz

5. Gain: Pin-programmable, closed-loop gain of ± 1 and ± 2

6. Bandwidth: 350 kHz full power bandwidth

Gain accuracy: 0.05% closed-loop gain accuracy

Offset voltage: 100μV channel offset voltage

Third, the application

Balanced modulation and demodulation

2. Simultaneous detection

Phase detection

Orthogonal test

5. phase sensitive detection

6. Phase lock amplification

Square wave multiplication

Five, circuit description

1. Lock-in amplifier mode

Connections: M1-B3, M1-B4, M1-B6 (amplified by a buffered amplifier with gain = 1 + R2 / R1)

Disconnect: others

Input: Test signal -> VIN, reference signal (usually square wave) -> REFIN

Output: VOUT -> Valid value of the useful frequency signal in the signal under test

Note:

1) The lock-in amplifier output passes through a fourth-order low-pass filter (cut-off frequency of 0.1Hz), indicating the effective value of the useful frequency signal.

2) To test the signal before passing the low-pass filter, test TP1.

2. Balance modulator mode

Connection: M2-B1, M2-B2, M2-B5 (without direct input through the amplifier)

Disconnect: others

Input: Baseband signal -> VIN, reference signal (usually square wave) -> REFIN

Output: VOUT -> Modulation signal

Note:

1) This mode can also be used as a precision rectifier to input the same signal to both inputs.

2) This mode can also be used as balanced demodulator, VIN input modulation signal, REFIN input carrier signal, VOUT output unfiltered baseband signal, so an external low pass filter is needed to filter low frequency baseband signal.

3. Other instructions

1) The supply voltage is plus or minus 5V to plus or minus 18V

2) The output of the low-pass filter is a DC signal whose magnitude is proportional to the effective value of the signal component of the same frequency as the reference signal in the input signal, that is,

3) low-pass filter, the higher the cut-off frequency, lock-in amplifier lock faster, but the output DC signal error.

Package include

1× AD630 Phase Lock Detector Weak Signal Conditioning Balanced Modulation Amplifier