Highly accurate CMOS Squave wave clock signal to drive MF5CN Audio filter
To eliminate the distortion of the duty cycle you want to generate your frequency at twice the desired value and then divide it by two using a D type FF (flip flop). Use a part such as a 74HC74 type. Connect your 2x frequency to the CLK pin of the flip flop. Then connect the D input pin to the inverted Q output. Take the Q output as the 1x frequency with very nice 50% duty cycle. The PRE and CLR inputs of the flip flop need to be pulled up to the positive supply rail via a resistor such as 10K ohms. Also remember to add a 0.1uF bypass capacitor between the V+ and GND pins at the chip.