Analog Top Talks in December on EDABoard.com forums

Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around analog ICs and analog design. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com.

Low Dropout Voltage Regulator (LDO) design – Read more

How to make a fast analog switch? – I would be grateful if someone could throw me a bone here, or a general idea of the direction would suffice, on how to make a fast analog switch that will do the following:

My challenge is to make an analog switch that is open during the first positive (half) period of PULSE. I’m personally thinking along the lines of a thyristor here…  Read more

What’s the difference between soft switching and hard switching? – In power amplifier design, I often find these two words. But I cannot find a clear and easy to understood answer between the difference. Read more

Power consumption of TDA8029 USIM controller with 3V/5V cards – In our board, two supply inputs of TDA8029 VDD, VDCIN are connected to 3.3V and we have support for 3V and 5V cards. We need to find the TDA8029 current consumption for the two cases below:

VDD=VDCIN=3.3V and 3V card
VDD=VDCIN=3.3V and 5V card
Below is a picture that shows current consumption for other cases.

There is no support from manufacturer currently. How do we interpolate/approximate the current for the above two cases? Read more

LPF’s cut-off frequency for signal acquisition with multiplexer – I have a 32-channel multiplexer with 32 signals (with maximum frequency of 10 Hz) connected to the inputs. By sweeping from ch-1 to ch-32, the output is read by an ADC through an amplification circuit. Could anyone tell me what the minimum cut-off frequency of the LFP at the ADC should be? Read more

Looking for audio amplifier for radio – I got an easy design for a ST TDA2822 but the only problem is TDA2822 original chip from ST is not available easily from a local supplier. A Chinese supplier has cheap TDA2822 but I have no idea whether it will work stable or not. Read more

Transition frequency of source follower circuit – Why is Cgs / gm approximately equal to ωT = 2π*(fT) , where fT is the transition frequency ? This is extracted from page 193 of Razavi book “Design of Analog CMOS Integrated Circuits” 2nd edition. Read more

Settling time issue in fully differential opamp – I have designed two-stage fully differential opamp. I took the results and it seems every parameter is giving good results except settling time (I believe). To check this, I connected in unity gain configuration and applied the pulse input of 500us (probably, I may be wrong in circuit setup). The output is not settling when I run the circuit. Read more

Bode plot of a PLL in time domain – How is possible to do stability analysis for the time domain PLL in Simulink? Read more

Purpose of transistors attached with source degeneration MOS – I can understand that transistor M14 and M15 are source degeneration MOS but what is the purpose of M3, M16 where M17 and M18 are biasing the transistor M14 and M15 gate? Read more