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Hi all: look at this interesting sar topology, which still uses redundancy technology and uses Main-Sub-DAC Array. In this capacitor array, the highest and second highest bits are "taken" from 22 unit capacitors, but only 11 unit capacitors are used in the high position capacitor array, and the...
Hi all, design a 12bits, 50MHz DAC. The schematic diagram is as follows. What puzzles me is how to determine the swing rate and bandwidth of the amplifier? I use a two-stage amplifier.
I assume that the output signal of the amplifier is V=A * sin (2 * 3.14 * f * t), so dV/dt = 2 * 3.14 * f *A *...
Hi all:
For the tow-thomas structure in the active filter, as shown in the figure below. There have been doubts about the phase margin of the amplifier!
We can design the amplifier's bandwidth to be relatively large, but at the same time how to consider the open-loop phase margin of the...
Hi BradtheRad, thax you to reply me. In fact, the resistance in the first stage can be calculated by NOISE, But I do not know how to design the resistance in the second stage and the third stage. Maybe the value of these resistances can be designed arbitrarily？
Hi all, I want to know how to design the R and C in the following CT modulator,
This circuit can be found in the book "Continuous Time Delta-Sigma AD Conversion" that was uploaded in the attachments, in chapter 7, at the page 179.
I think R1 and RDAC1 can be found from SNR, but how to design...
Use AMS to simulate circuit, then "The primitive 'psp103' couldn't be found", why?
Hi all, I use IC617 to design some circuit, because there has Verilog code, so I want to use AMS to simulate circuits. But there have errors:
The primitive 'psp103' couldn't be found when attempting to create...
Hi frankrose, I don't think that the 2nd OPA has no function. In fact because of the large size of PMOS, if there have no the 2nd OPA, the pole of VG will be very small, and the stability will not be well. Now there have the 2nd OPA, the resistance of VG is 1/gm, so the pole will be large.
Hi all, I am designing a LDO which can as a power supply for SRAM. The following picture is the construction of the LDO.
There have two OPA, i.e. OPA1 and OPA2. Now the frequency of reading and writing SRAM is 60MHz, There have some questions:
1.How can I confirm the GBW of OPA1 and OPA2?
2.How...
Hi all, after a long time, I come back again
Hi t4_v, Hi erikl , I connect the gate of NM0 to VB rather than VIP, and the OPA works well.
I have a question yet: my circuit is a pure DC circuit, does it mean that this circuit not need ac simulation at all? But it is a negative feedback！
Hi all: I perform the ac simulation for the circuit. the bode curve is the picture above. From the curve, we can know that the PhaseMargin is bad. But if I connect the gate of NM0 to VB other than VIP, the bode curve is very good!
If the gate of NM0 is connected to VB, the VIP is the positive...
Hi all, I am designing a circuit shown in the picture below
In this circuit, there have a NMOS whose name is NM0. I don't understand what's the role of it.
In fact, this circuit is a power supply and produces a 1V voltage to a DLL (delay phase lock).
How can I understand the nmos NM0? what's...
Hi erikl: from the foundry process datasheet, the size of Q2 &Q4 can not be reduced any more. Maybe the only thing I can do is more connections between Co_sub and metel one in the layout to reduce R0.
For the transistor Q321, I can't access Co_sub, but I can disconncet all connections of...
Hi all, Hi erikl：I'm glad to see you again!
It's cost me so long time to analyse the big current, now I want to write something:
At first, upload two figure again:
Look at these two figure: the left figure is a bipolar Q1, but in this bipolar, there have a parasitic transistor Q0 whose emitter...
Hi erikl: yes, I do analyze the circuit by simulation, and I don't think the simulation is useful. From simulation, Q1~Q4 have no current, the current of Q321 and Q343 is only 80mA. But from testing result, the current is so big!! and from the testing result I think there have big current from...
Hi erikl: In fact, the most current goes through the transistors Q1~Q4 ,Q321 & Q343, as shown by the picutre which I uploaded in #4. In that picture, the color of this transistors is red which meas the current is very big!
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