Unformatted text preview: Category: Waveforms & Filters CIRCUIT IDEAS FOR DESIGNERS Schematic no. wf_47003.0 Function Generator Description This circuit utilizes a quad operational amplifier to produce 4 outputs at the 4 stages, consisting of a square wave output, a triangle wave output, a sine wave output and –2X gain amplifier respectively. The first stage functions as a square wave generator. Initially, assume that its output is at V+ (+2.5V). The +input voltage is determined by the ratio of the resistor divider, which, in this case, are the 27K and the 100K resistors. The output signal feeds back to +ve input terminal via the resistor network, with the operational amplifier acting as a comparator. A RC network charges the capacitor at –ve input terminal until the voltage crosses that at the +input voltage. At that point the output of the amplifier changes state to V- (–2.5V) as a result of amplifying now a negative input signal. The voltage on the +ve input terminal changes to a negative of the resistor divider ratio voltage. The RC network begins to discharge toward V-. When the voltage at –ve input terminal crosses below +ve input voltage, the output flips again to V+. Therefore the circuit functions as an oscillator, generating a square wave. When this square wave is integrated at the second stage, a triangle wave is generated at the output. Another integration of this triangle wave through the third stage produces a sine wave signal at the output of the third stage. The fourth and last stage is merely a standard inverting amplifier with a gain equal to –2. Recommended Components ALD4701, ALD4702, ALD4704, ALD4706 Other Related Circuit Ideas Schematic no. wf_47001.0 Micro-power Band-pass Network Schematic no. wf_47002.0 Band-pass Network Schematic no. wf_47004.0 Low-Pass Filter (RFI Filter)
2005 Advanced Linear Devices, Inc. Information furnished by Advanced Linear Devices, Inc. (ALD) is believed to be accurate and reliable. However, ALD assumes no responsibility for the use of such information nor for any infringement of patent or rights of third parties that may result from its use. No license is granted implication or otherwise under any patent rights of ALD. www.aldinc.com ...
View Full Document
- Spring '08
- Square wave, Sine wave, 100K, 27K, input terminal, Advanced Linear Devices