DSB-SC AM Generation with AD633 Analog Multiplier IC

In the field of electronics, signal modulation is a crucial technique that helps in the transmission of data over long distances. Amplitude modulation (AM) is one of the most popular modulation techniques that are widely used in radio broadcasting, telecommunications, and other communication applications. DSB-SC AM signal can be generated using discrete diodes and transistors(see AM modulator using JFET transistor) or one can use ready made integrated circuit like MC1496 balanced modulator demodulator IC or analog multiplier IC like AD633 and AD734. In this post, we will explore the process of generating Double Sideband Suppressed Carrier (DSB-SC) AM signal using AD633 Analog Multiplier IC.

DSB-SC AM Generation

DSB-SC AM is a type of AM signal that involves the removal of the carrier signal from the modulated signal. The process of generating DSB-SC AM signal involves multiplying the modulating signal with a carrier signal. This process results in the generation of a DSB-SC AM signal.

AD633 Analog Multiplier IC

The AD633 is a popular analog multiplier IC that can be used in various applications, including signal processing, modulation, and demodulation. The AD633 multiplier IC is designed to perform the multiplication of two analog signals with a high level of accuracy and precision.

The AD633 integrated circuit pin out diagram is shown below.

The pin defination is shown below.

The AD633 output W is given by the following equation,

\( W = \frac{(X1-X2)(Y1-Y2)}{10} + Z \)

DSB-SC AM Generation with AD633 To generate a DSB-SC AM signal using AD633, we need to follow the following steps:

Step 1: Input signal

The input signal is the modulating signal that we want to use to modulate the carrier signal. In this case, we can use a sine wave or any other signal that we want to modulate.

Step 2: Carrier signal

The carrier signal is a high-frequency signal that we want to modulate with the input signal. In this case, we can use a sine wave or any other high-frequency signal that we want to modulate.

Step 3: AD633 connection

To generate the DSB-SC AM signal, we need to connect the input signal to one of the input pins of the AD633 IC and the carrier signal to the other input pin. The output pin of the AD633 IC will generate the modulated signal.

Step 4: Output signal The output signal will be a DSB-SC AM signal that contains only the modulating signal.

DSB-SC AM AD644 Circuit Diagram

The following shows the circuit diagram that generates DSB-SC AM signal using the message signal and the carrier signal inputs.

In the above circuit diagram, the message signal is connecting to the X1 pin and the X2 pin is grounded. The carrier signal is connected to the Y1 pin and the Y2 pin is grounded. The DSB-SC signal appears at the W pin. The summing pin Z is grounded. The AD633 IC is powered using +5V and -5V. The power connection are grounded using the 0.1uF capacitors C1 and C2.

The following shows the message signal, the carrier signal and the DSB-SC AM signal on oscilloscope.

The following shows the spectrum of the output signal from the above AM modulator circuit.

The above frequency spectrum shows that the output signal from the AD633 based AM modulator circuit is indeed DSB-SC AM signal since the carrier signal component is suppressed at 40KHz.

Video demonstration

In the video demonstration below it is shown how the AD633 analog multiplier IC can be used for generation of DSB-SC AM signal.

Conclusion

In conclusion, generating DSB-SC AM signal using AD633 analog multiplier IC is a simple and effective technique that can be used in various communication applications. The process involves multiplying the input signal with a carrier signal, followed by the removal of the carrier signal using a bandpass filter. The AD633 IC is an excellent choice for this purpose, as it provides high accuracy and precision in signal multiplication.

References:

[1] AM modulator using MC1496 modulator(Standard AM)

[2] How MC1496 Balanced Modulator Works?(DSB-SC AM)

[3] Envelope Detector Circuit for AM Demodulation