VCO Circuit | Electronic Project Circuits

Posts Tagged ‘VCO circuit’

1.2GHz VCO With Linear Modulation

Since high frequency voltage-controlled oscillators, or VCOs, are not easy to construct, Maxim (www.maxim-ic.com) has produced an integrated 1.2GHz oscillator, the MAX2754. The center frequency is set using the TUNE input, and a linear modulation input allows the frequency to be modulated. The IC is available in an 8-pin µMAX package, operates from a supply of between 2.7 V and 5.5 V, and draws a current of less than 2 mA. Both TUNE and MOD operate over control voltage range of +0.4 V to +2.4 V. TUNE allows the VCO frequency to be adjusted from 1050 MHz to 1270 MHz. In some applications a PLL control voltage will be applied here, allowing the center frequency to be set exactly to a desired value.
For simplicity in the circuit diagram we have shown a potentiometer. The MOD input allows the VCO to be modulated in a digital or analogue fashion, with a transfer slope of –500 kHz/V. In the circuit we have shown an example where MOD is used for frequency shift keying (FSK) modulation. Resistors R1 to R4 shift the level of the data signal so that it has a center value of +1.4 V and an amplitude corresponding to the desired frequency deviation. One example set of values, suitable for use with a 5 V power supply, is as follows: R1 = 480 ?, R2 = 100 ?, R3 = 220 ? und R4 = 270 ?. [...]
Source: http://www.extremecircuits.net/2010/07/12ghz-vco-with-linear-modulation.html

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Categories: Converter Circuit, Oscillator generator Tags: high frequency vco, VCO circuit, Voltage to frequency converter

Voltage controls sine-wave frequency

The circuit in Fig 1 generates a 50-Hz to 1-kHz sinusoidal waveform that exhibits lower than 60-dB THD. The input voltage controls the output frequency with the relationship 1 kHz/V. The output amplitude is invariant with frequency over the entire operating range. IC1 is a V/F converter with an input control range of 0 to 1V. You adjust R5 so that the output frequency equals 1 kHz with a 1V. [...]

VCO – Analog to Digital by LM331

This Circuit is a simple Analog to Digital Interface with a capability of 10 to 12 bits resolution. 10 bits means 1024 counts or parts of a full scale FS which is close to 3-1/2 1999 counts. In this 1 V can be read as 1.000 V that means even 1mV can be resolved for FS of 1V.
The Caps C6 and others must be plastic multilayer low-leakage types for accuracy of reading. Use all 1% MFR 100ppm or better resistors, Design gain of U1B for the Full Scale you want. The Output Fout is a Frequency which is directly proportional to the measured voltage Vin.
The pulses can be isolated using opto-couplers to avoid ground loops or electric hazard. An additional protection and scaling circuit at the input may be required for some sensors.