Guest Alun Posted June 18, 2005 Report Share Posted June 18, 2005 I wasn't really thinking, I just copied the cmos inverter circuit, how come it doesn't blow up then? Quote Link to comment Share on other sites More sharing options...
audioguru Posted June 18, 2005 Report Share Posted June 18, 2005 Hi Alun,Your Mosfet amplifier will provide only 6.2W to an 8 ohm load at clipping, but draw 600W from a 20V supply. Very inefficient! :o :oAn ordinary CD4069 Cmos inverter draws only about 1mA with a 5V supply, about 5mA with a 10V supply and about 10mA with a 15V supply when used as a linear amp.A 74HC04 inverter will draw from 10mA to 30mA (beyond its 25mA max output rating) with a 5V supply when used as a linear amp, so they are not recommended for use as a "Classic Cmos 2-inverter oscillator". ;D Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted June 18, 2005 Report Share Posted June 18, 2005 Hi Alun,Your Mosfet amplifier will provide only 6.2W to an 8 ohm load at clipping, but draw 600W from a 20V supply. Very inefficient! :o :oIt's ok you don't need to tell me, don't worry I understand ;D and I can see my error, both of the mosfets will be biased on all the time and it will operate in class A. The gate of the P-channel will always be lower and the source turning it on and the N-channel will always have the gate above the source turining it on too, as both transistors are on the power consumption will be very high.An ordinary CD4069 Cmos inverter draws only about 1mA with a 5V supply, about 5mA with a 10V supply and about 10mA with a 15V supply when used as a linear amp.A 74HC04 inverter will draw from 10mA to 30mA (beyond its 25mA max output rating) with a 5V supply when used as a linear amp, so they are not recommended for use as a "Classic Cmos 2-inverter oscillator". ;DI know amazing isn't it?The internal diagram looks very similar to my circuit, but why is mine a power wasting class A amplifier and the CMOS inverter an effiecnt class B/AB amplfier?How do they ensure that both of the transistors don't turn at the same time?Do the diodes and input resistor have some magic property or something? ;DCD4096_cmos_inverters.pdf Quote Link to comment Share on other sites More sharing options...
audioguru Posted June 19, 2005 Report Share Posted June 19, 2005 An ordinary CD4069 Cmos inverter draws only about 1mA with a 5V supply, about 5mA with a 10V supply and about 10mA with a 15V supply when used as a linear amp.A 74HC04 inverter will draw from 10mA to 30mA (beyond its 25mA max output rating) with a 5V supply when used as a linear amp, so they are not recommended for use as a "Classic Cmos 2-inverter oscillator". ;DI know amazing isn't it?The internal diagram looks very similar to my circuit, but why is mine a power wasting class A amplifier and the CMOS inverter an effiecnt class B/AB amplfier?How do they ensure that both of the transistors don't turn at the same time?They do turn on at the same time in class-A. That is why they draw supply current. But they are puny little thingys (for speed) with a fairly high "on" resistance.A power Mosfet has thousands of bigger Mosfets, called cells, in parallel. That's why their input capacitance is so high, and their "on" resistance is so low. ;D Quote Link to comment Share on other sites More sharing options...
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