Combi-gate Oscillator IC

Many of you will know that a digital oscillator built from unbuffered inverters in a 74xx04U IC has to be followed by a ‘normal’ gate. Both functions are now available from a single IC produced by Philips.A quartz crystal oscillator built around an unbuffered logic gate type 74HC04U traditionally employs a high feedback resistance to be effectively turned into a high-gain linear amplifier (Figure 1). The frequency-determining quartz crystal is also inserted in the feedback path, its resonance characteristics forcing the circuit to oscillate at the crystal frequency.