48 Mhz Cmos Oscillator

017 48 MHZ CMOS OSCILLATOR Crystal oscillators using digital gates generally do not generate frequencies above 30 MHz, because the necessary crystals are not allowed to oscillate on their fundamental frequency. In the oscillator shown here, the crystal is forced to oscillate on the third harmonic since it is connected in series with a parallel tuned circuit that resonates at the fundamental of 16 MHz. For digital applications, the output of N1 may be enhanced by the use of a second inverter. The circuit will operate satisfactorily only if non-buffered cmos devices are used. Gates from the Hcu family will enable operation up to 60 MHz. TEST & MEASUREMENT 6A 6V SA 5Y •A 12112113WEIDU 11"11 b El El E el El El E IA IV 2A 2Y 3A 1 N1, N2= 1/3 74 HCU 04 894051 - 11 13