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.

Adaptive biasing of source degeneration – I am designing an OTA with improved linearity, and I have used source degeneration technique, and the source degeneration is a MOS resistor operating in triode region. I don’t know how to adaptively bias the gate voltage of the triode MOS (source degenerated). Read more

Latching Relay vs FlipFlop Circuit – I am designing a circuit that every time a switch is pressed the output latches to the opposite state. I will repeat this circuit 10 times for 10 switches. Regarding reliability, what is the most reliable circuit, the relay or the flipflop latch design? Read more

How to design DC-DC to let output voltage follow input voltage – I’m totally new in this DC part. I want to design a circuit:
DC input, voltage changes from 0 to 4V
DC output, voltage follow input to change. For example,
input=0， output=0
input=1, output=1
input=2,output=0
input=3,output=1
input=4,ouput=0

Like below, x-axis is Vin; y-axis is Vout. Which kind of circuit or architecture should I use? Read more

What SSR and associated circuit should I use? – I have a Mighty Mule driveway alarm that has both an LED and a piezo buzzer output signal. The LED signal stays on after activation and is therefore unusable for my purposes. The buzzer signal is momentary, so I want to use that to activate another device. The signal to the buzzer that I want to use varies from 1.2V – 1.9V DC at a max of 12mAmps. The device I want to control is the transmitter of a remote doorbell. The doorbell is normally activated by a small push button that closes a circuit that carries 12V DC at less than 120mAmps. I could use a mechanical relay for this but I would like to go electronic to save space and for reliability. The question is can I use an SSR to accomplish this and if so which one would be appropriate? Read more

High power LED matrix connection – I need your help. I am building a high power LED matrix, and I need advice on how to connect individual leds. I have a 260x160mm heat sink, where I will mount star PCB leds. PCBs are 20mm wide and I need to space them 3mm apart from each other for lens to fit on. So I can put them 11×6. How should I connect LEDs to a power supply in the meaning of serial-parallel connection, so that I won’t damage any led and that all would be as bright as possible? Read more

Tri-state MOSFET switch – I need a tri-state discrete MOSFET switch, to switch among +V, -V and GND. I thought to use a couple of complementary MOSFET pair as in the attached image. Is there a problem of leakage current when one of the pair is high impedance (bottom pair when output is +5V, top pair when output is -5V)? Read more

9V-32V step down to 5V switching regulator – My professor wants us to design a switching regulator with an input of 9V to 32V, which will be regulated to 5V. Our circuit design is shown below. I thought that the design is a switching regulator since it has a switching waveform and an efficiency of 81 to 87% according to my simulation. I don’t quite understand what he meant that it is not a switching regulator instead of a linear regulator since there’s no feedback. I thought lm393 provides the feedback. Please help me understand how can we say that it is switching or linear regulator. Read more

Bizzare buffer AC response – In one of my schematic level designs, for an analog amplifier, PM is supposedly 92 degrees. But when I used it in a buffer configuration, I noticed that for a square pulse, there were ringing during the slewing! I never experienced something like that. It could ring during settling and stuff, but during slewing? There is possibly a zero in the system, it is causing the phase go up and down for a while when the freq increased, but it never causes PM to be problematic. Read more

Frequency response heterojunction bipolar transistor – First I need to find a circuit to analyze/study the frequency response of heterojunction bipolar transistor, then simulate that circuit on SPICE (I’m using Orcad Cadence). Can someone help me find a circuit as mentioned above? I’m having difficulties finding one. Read more

RelXpert Simulator working principle in background – I would like to know more about RelXpert simulator and how it calculates the age. What is the basic principle RelXpert works on? Anybody with any inputs on this or any good materials or links to know more about the background simulation steps? Read more