khorlipmin
Member level 3
My VCO performed badly for frequency pushing. I wonder if I had tested it in the wrong way. hope someone can help out. The differential current controled oscillator uses triple feedback. I tested it with a current sourse at the NMOS bias current and the PMOS load is controlled by a control voltage. The question is when I vary the supply voltage, should the supply voltage to the current source and the control voltage changes as well? When I have all these parameters changed, the slope is around 300MHz/V, if only the supply voltage changes independently, the figure doubled.
I am thinking that I should include the replica biasing circuit before I test it for frequency pushing, as when the supply voltage goes up, the biasing current will decrease which is the opposite case of a CCO core test with independent current source.
Thanks
I am thinking that I should include the replica biasing circuit before I test it for frequency pushing, as when the supply voltage goes up, the biasing current will decrease which is the opposite case of a CCO core test with independent current source.
Thanks