APPLICATION NOTE
4
.param H=1 * V1 in 0 SIN (0 1 1) Xrms 1 rms RMSXhys 1 hys HYS param: H=1 * .tran
10m 1 .end
A 1Hz sine wave is used for the stimulus to the RMS and HYS circuits.
Figure 6: Output from RMS and HYS Circuit
Figure 6 shows a Probe plot of the input, and the outputs from each circuit. Note that the RMS circuit outputs the
well-known result of 0.707 volts after one input cycle, while the HYS circuit lags the input by a half volt in
each direction for a total hysteresis of one volt.
Amplitude and Balanced Modulation
Multipliers
Multiplier is a behavioral block that performs the mathematical task of multiplying the two inputs, and returns the
product as the output. Multipliers are often used for signal processing applications. In this note, two examples are
presented to illustrate the use of a multiplier to make an amplitude modulator, and to make a frequency doubler.
Amplitude Modulation
Amplitude modulation is a technique which uses a low frequency signal to control the amplitude of a high-
frequency signal. A simple modulator can be constructed using a multiplier as shown in Figure 7:
