assemelgohary
Newbie level 1
I am building BLE receiver, and I am responsible for the ADC block, so currently I am designing the comparator and I have several questions. The ADC is using SAR logic, it is 11 bit and the sampling rate would be 10 MS/s. So first I want to know what is the required speed of the comparator and how to calculate it?
secondly, I am now designing the basic comparator to learn through it how to control the comparator and then I am going to design a StrongArm Comparator to be lower in power. So I have attached the basic comparator schematic
I have made all transistors in the saturation region ( 2 ) in the DC analysis, and now I want to know the gain of my preamplifier and how to judge my comparator to know good it is?
so how should I know the gain of my preamplifier ? ( I have used ac analysis and plotted ( Vx - Vy / Vinp1 - Vinp2 ) but I am getting a very small gain and i know that the gain of the preamplifier should be in the range of 2 to 10 ?
so basically my question how to measure the gain what are the inputs i should include ? what type of input sources should i use ? my Vcm is 750 mv , I tried to insert a sine wave from one input with dc value 750 mv and ac amplitude 10 mv and from the other input an ac amplitude of -10 mv, but the gain was too small ? so also i have got another question which is how to control the preamplifiers gain ? is it just through the W/L of the differential pair ?
After all that I want to know what simulations i should do and what analysis and inputs i should use to design my Comparator ?
secondly, I am now designing the basic comparator to learn through it how to control the comparator and then I am going to design a StrongArm Comparator to be lower in power. So I have attached the basic comparator schematic
I have made all transistors in the saturation region ( 2 ) in the DC analysis, and now I want to know the gain of my preamplifier and how to judge my comparator to know good it is?
so how should I know the gain of my preamplifier ? ( I have used ac analysis and plotted ( Vx - Vy / Vinp1 - Vinp2 ) but I am getting a very small gain and i know that the gain of the preamplifier should be in the range of 2 to 10 ?
so basically my question how to measure the gain what are the inputs i should include ? what type of input sources should i use ? my Vcm is 750 mv , I tried to insert a sine wave from one input with dc value 750 mv and ac amplitude 10 mv and from the other input an ac amplitude of -10 mv, but the gain was too small ? so also i have got another question which is how to control the preamplifiers gain ? is it just through the W/L of the differential pair ?
After all that I want to know what simulations i should do and what analysis and inputs i should use to design my Comparator ?